JP6488213B2 - Insulating cold shrink tube for cable connection and cable connection - Google Patents

Description

  The present invention relates to a normal temperature shrinkable tube used for connecting a cable such as a CV cable (crosslinked polyethylene insulation cable), and a cable connecting portion using such a normal temperature shrinkable tube.

  Conventionally, in an intermediate connection portion and a termination connection portion of a power cable such as a CV cable, or a connection portion in a communication cable terminal or the like, an insulating cold shrink tube is used for the purpose of waterproofing, protection, insulation reinforcement, and the like ( For example, see Patent Document 1.)

  This room temperature shrinkable tube is a cylindrical body made of an elastic rubber material such as ethylene propylene rubber, and is in a contracted state at room temperature. For this reason, when mounting, it is necessary to preliminarily expand the cold shrink tube (hereinafter referred to as diameter expansion), and in order to maintain this expanded state, an expanded diameter holding member called an inner core is placed in the cold shrink tube. Inserted (usually stored in a state where the inner core is mounted inside, that is, a cold shrink tube with an inner core). And it is arrange | positioned in the location which should be mounted | worn with the inner core inserted, Then, by pulling out an inner core, a normal temperature shrinkable tube shrink | contracts and it is mounted | worn in a predetermined position.

Such room-temperature shrinkable tubes have excellent flexibility due to diameter expansion, and good permanent elongation characteristics and stress relaxation characteristics (compression set) to ensure adhesion to the mounted surface after the inner core is pulled out In addition, it is required to have excellent damage resistance during use and storage (expansion of diameter) and to have good insulation.
The present applicant has developed a tube made of a rubber composition in which silica, process oil, vulcanizing agent and the like are added based on ethylene propylene rubber as a normal temperature shrinkable tube satisfying such required characteristics, and has previously filed an application (for example, , See Patent Document 2).

  However, the rubber composition was not sufficient in extrudability, especially surface smoothness, due to the influence of silica moisture absorption. For this reason, attempts have been made to improve the flowability of the rubber composition during extrusion by increasing the blending amount of process oil or using low-viscosity ethylene propylene rubber as the base polymer. On the other hand, the extrusion processability is improved, but the permanent elongation characteristics are lowered.

JP 2007-87664 A JP 2012-151074 A

  The present invention has been made in order to solve the above-mentioned problems, and has an insulating cold-shrinkable tube for cable connection parts that has good flexibility, permanent elongation characteristics, stress relaxation characteristics and insulation properties, and excellent surface smoothness, And it aims at providing the cable connection part provided with such a normal temperature shrinkable tube.

In order to achieve the above object, the present invention has the following embodiments [1] to [8].
[1] A composition containing (B) 50 to 70 parts by mass of carbon black and (C) 30 to 40 parts by mass of (C) calcined clay with respect to 100 parts by mass of (A) ethylene / propylene / diene terpolymer. An insulating cold-shrinkable tube for a cable connection part, characterized by comprising a crosslinked product of
[2] Insulating cold shrinkage for cable connection parts, wherein the composition contains (B) component and (C) component in a total of 80 to 100 parts by mass with respect to 100 parts by mass of component (A) tube.
[3] Component (A) is an ethylene / propylene / diene ternary copolymer having (a-1) ethylene content of 50 to 55 mass%, diene content of 3 to 5 mass%, Mooney viscosity ML _{1 + 4} (125 ° C.) 60 to 90 60-80% by mass of polymer, and (a-2) ethylene / propylene / diene ternary copolymer having ethylene content of 40-70% by mass, diene content of 3-6% by mass, Mooney viscosity ML _{1 + 4} (125 ° C.) of 120 or more The insulating normal temperature shrinkable tube for a cable connection part according to [1] or [2], comprising 20 to 40% by mass of the coalescence.
[4] The composition comprises (i) Mooney viscosity ML _{1 + 4} (100 ° C.) 20 to 40, (ii) durometer hardness 30 to 60, (iii) tensile strength 7 MPa or more, and (iv) tensile elongation 600% or more. (V) Permanent elongation 15% or less and (vi) Volume resistivity 1 × 10 ¹² Ω · cm or more, [1] to [3] Insulation for cable connection part Cold shrink tube.
[5] The composition according to any one of claims 1 to 4, wherein the composition further comprises (D) 60 to 100 parts by mass of process oil with respect to 100 parts by mass of component (A). Insulating cold shrink tube for cable connection.
[6] (B) component, the average particle diameter of 40 to 60 nm, and wherein the carbon black iodine adsorption amount 30 to 50 mg / g, DBP absorption amount 100~120cm ³ / 100g [1] to [5 ] The insulation normal temperature shrinkable tube for cable connection parts in any one of.
[7] The insulating room temperature shrinkable tube for cable connection part according to any one of [1] to [6], wherein the component (C) is a fired silica surface-treated with a silane coupling agent.
[8] A cable connection part comprising the insulating normal temperature shrinkable tube for cable connection part according to any one of [1] to [7].

  According to the present invention, an insulating room temperature shrinkable tube for a cable connection portion having excellent flexibility, permanent elongation characteristics, stress relaxation characteristics and insulation, and excellent surface smoothness, and such a room temperature shrinkable tube are provided. A cable connection is provided.

It is sectional drawing which shows the cable connection part which concerns on one Embodiment of this invention.

  Embodiments of the present invention will be described below.

  The insulating cold-shrinkable tube for cable connection part of the present invention (hereinafter sometimes simply referred to as “cold-shrinkable tube”) is (A) 100 parts by weight of ethylene / propylene / diene terpolymer ( B) It is comprised with the crosslinked body of the composition containing 50-70 mass parts of carbon black, and (C) 30-40 mass parts of baked clay.

  The ethylene / propylene / diene terpolymer (EPDM) as the component (A) is not particularly limited, such as the type and content of the diene component, the ethylene content, and the molecular weight. It can be appropriately selected and used. Specifically, for example, ethylene and propylene obtained by copolymerizing ethylidene norbornene, dicyclopentadiene, 1,4-hexadiene, etc. as a diene component are used.

From the viewpoint of extrudability, permanent elongation characteristics and stress relaxation characteristics, the combined use of the following (a-1) and (a-2) EPDM is particularly preferable as the component (A).
(A-1) EPDM having an ethylene content of 50 to 60% by weight, a diene content of 3 to 5% by weight, and a Mooney viscosity ML _{1 + 4} (125 ° C.) of 60 to 90
(A-2) EPDM having an ethylene content of 40 to 70 mass%, a diene content of 3 to 6 mass%, and a Mooney viscosity ML _{1 + 4} (125 ° C.) of 120 or more

Examples of commercially available EPDM products of (a-1) and (a-2) include (a-1) EPDM, for example, Esprene 532 (trade name; ethylene content 51% by mass, manufactured by Sumitomo Chemical Co., Ltd.) Diene content 3.5% by weight, Mooney viscosity ML _{1 + 4} (125 ° C.) 81), Esprene 552 (trade name; ethylene content 55% by weight, diene content 4.0% by weight, Mooney viscosity ML _{1 + 4} (125 ° C.) 85 ), Esprene 502 (trade name; ethylene content 56 mass%, diene content 4.0 mass%, Mooney viscosity ML _{1 + 4} (125 ° C.) 62), JSR EP25 (trade name; ethylene content 58.62) manufactured by JSR Corporation. 5% by weight, diene content 5.1% by weight, Mooney viscosity ML _{1 + 4} (125 ° C.) 63), JSR EP103AF (trade name; ethylene content 59% by weight, die Content of 4.5% by weight, Mooney viscosity ML _{1 + 4} (125 ° C.) 87).
(A-1) As EPDM, EPDM having an ethylene content of 50 to 55% by mass, a diene content of 3 to 5% by mass, and a Mooney viscosity ML _{1 + 4} (125 ° C.) of 70 to 90 is preferable.

Further, (a-2) EPDM is commercially available as an oil-extended rubber, for example, Esprene 601F manufactured by Sumitomo Chemical Co., Ltd. (trade name; ethylene content 59% by mass, diene content 3.5% by mass, Mooney Viscosity ML _{1 + 4} (125 ° C.) 73, oil extended amount 70 phr), Mitsui EPT 3072EM (trade name; ethylene content 64 mass%, diene content 5.4 mass%, Mooney viscosity ML _{1 + 4} (100 ° C.) manufactured by Mitsui Chemicals, Inc. ) 51, oil extended amount 40 phr), and the like.
(A-2) EPDM is preferably EPDM having an ethylene content of 40 to 60% by mass, a diene content of 3 to 5% by mass, and a Mooney viscosity ML _{1 + 4} (125 ° C.) of 70 to 90.

  The preferable mixing ratio of the EPDM of the above (a-1) and (a-2) is 60-80% by mass of (a-1), more preferably 65-75% by mass, and 20-40 of (a-2). It is 25 mass%, More preferably, it is 25-35 mass%. When the ratio of (a-1) is less than the above range, or the ratio of (a-2) exceeds the above range, the properties of permanent elongation and stress relaxation may be defective. Moreover, when the ratio of (a-2) is less than the above range, or when the ratio of (a-1) exceeds the above range, the extrudability may be poor.

As the carbon black of component (B), furnace black, channel black, thermal black, and the like can be used. Of these, furnace black is preferable from the viewpoint of improving extrudability (particularly surface smoothness), permanent elongation characteristics, mechanical characteristics, and the like. Good extrudability furnace carbon black (FEF) and general-purpose furnace carbon black (GPF) are preferred. More preferred.
Carbon black has an average particle diameter of 40 to 60 nm, an iodine adsorption amount of 30 to 50 mg / g, and a DBP absorption amount of 100 to 120 cm ³ / from the viewpoint of improving extrudability (particularly surface smoothness). 100 g of carbon black is preferred. Moreover, if an average particle diameter is the said range, tensile strength and hardness will become favorable. That is, when the average particle diameter is less than 40 nm, the hardness increases, and when the average particle diameter exceeds 60 nm, the tensile strength decreases. That is, it is difficult to increase the diameter in advance when the cold-shrinkable tube is attached to the cable connection portion.
The average particle diameter is a value measured by electron microscopy (arithmetic average particle diameter), the iodine adsorption amount and the DBP absorption amount are both characteristic values defined in JIS K6217, and the DBP absorption amount is A It is the value measured by the method.
Specifically, for example, Asahi # 60, Asahi # 55 manufactured by Asahi Carbon Co., Ltd., Seest V manufactured by Tokai Carbon Co., Ltd., Seest SO, HTC # 100 manufactured by Shin Nikka Carbon Co., Ltd. In any case, the trade name) is preferably used. Carbon black may be used individually by 1 type, and 2 or more types may be mixed and used for it.

  The blending amount of the carbon black of component (B) is in the range of 50 to 70 parts by mass per 100 parts by mass of component (A). When the blending amount is less than 50 parts by mass, the extrusion processability (particularly the surface smoothness) cannot be sufficiently improved, and the permanent elongation characteristics, mechanical characteristics and the like are also deteriorated. When it exceeds 70 mass parts, volume resistivity will fall and it will become difficult to maintain insulation. In addition, the hardness increases and it becomes difficult to pre-expand the diameter when the cold-shrinkable tube is attached to the cable connection portion. The preferable range of the compounding amount of carbon black is 50 to 60 parts by mass per 100 parts by mass of component (A).

  The calcined clay of component (C) is a mineral filler mainly composed of aluminum silicate, and its particle size is not particularly limited, but in terms of mechanical properties, the average particle size is 1.0 to 1.5 μm. Those are preferred. In addition, the average particle diameter of this baked clay is a 50% particle diameter (D50 value) in the number cumulative distribution measured by a laser diffraction particle size distribution analyzer. The surface of the baked clay may be surface-treated with a silane coupling agent or a titanate coupling agent. In particular, sintered clay treated with a vinylsilane coupling agent such as vinyltrimethoxysilane or vinyltriethoxysilane is not treated with untreated fired clay or other coupling agent such as 3-aminopropyltrimethoxysilane. Compared to the treated baked clay, high mechanical properties are obtained, which is preferable.

  Specifically, for example, Translink Clay 37, Translink Clay 445, Satinton W (all of which are trade names) manufactured by BASF, etc. are used, and in particular, the transformer treated with a vinyl silane coupling agent. Link clay 37 is preferably used. A baked clay may be used individually by 1 type, and 2 or more types may be mixed and used for it.

  The amount of the component (C) calcined clay is in the range of 30 to 40 parts by mass per 100 parts by mass of the component (A). When the blending amount is less than 30 parts by mass, the volume resistivity is lowered and it is difficult to maintain insulation. If it exceeds 40 parts by mass, the extrudability (particularly the surface smoothness) cannot be sufficiently improved.

  In addition, the composition of the present invention includes an insulating filler other than the above baked clay, for example, silica, talc, mica, calcium carbonate, magnesium hydroxide, aluminum hydroxide, sulfuric acid, as long as the effects of the present invention are not impaired. Barium, titanium oxide, glass fiber and the like may be blended, and clay other than the calcined clay, such as hard clay, may be blended. Calcium carbonate includes heavy calcium carbonate obtained by pulverizing limestone and precipitated calcium carbonate that is chemically synthesized, any of which can be used.

  In the present invention, (B) component and (C) component, or (B) component, (C) component, and other insulating fillers in a total amount of 80 to 100 parts by mass of component (A). It is preferable to blend 100 parts by mass. When the amount of the component (A) is less than 80 parts by mass per 100 parts by mass of the component, the die swell at the time of extrusion process becomes large, and the surface smoothness may not be sufficiently improved. Moreover, when it exceeds 100 mass parts, the hardness after hardening will become high too much and there exists a possibility that the prior diameter expansion at the time of attaching a normal temperature shrinkable tube to a cable connection part may become difficult.

(D) Process oil, (E) Zinc oxide, and (F) Vulcanizing agent can be mix | blended with the composition of this invention as an arbitrary component.
The process oil of component (D) mainly has an effect of improving processability. The process oil is not particularly limited and may be any of a paraffinic process oil, a naphthenic process oil, and an aromatic process oil, but improves the extrusion processability and has good mechanical properties. Paraffinic process oil is preferable from the viewpoint of obtaining the above. Specifically, for example, Diana Process Oil PW-90, Diana Process Oil PW-380 manufactured by Idemitsu Kosan Co., Ltd., Process Oil P300 manufactured by JX Nippon Oil & Energy Corporation, Super Oil N100 (or more, any Also, a trade name of paraffinic process oil is preferably used. One process oil may be used alone, or two or more process oils may be mixed and used.

  The blending amount of this process oil (when an oil-extended EPDM is used, including the extended oil component blended therein) is preferably in the range of 60 to 100 parts by mass per 100 parts by mass of component (A). When the blending amount is less than 60 parts by mass, the Mooney viscosity of the rubber composition increases, and the extrusion processability decreases. Moreover, there is a risk of poor dispersion during kneading. When it exceeds 100 parts by mass, the green strength is lowered, and the permanent elongation characteristics and mechanical characteristics after curing are also lowered. A more preferable range of the blending amount of the process oil is 50 to 90 parts by mass and more preferably 60 to 80 parts by mass per 100 parts by mass of the component (A).

  Component (E), zinc oxide, mainly has an effect of improving processability. Various zinc oxides are known depending on the production method thereof, and any zinc oxide commercially available as an additive for rubber can be used without particular limitation. Zinc oxide may be used alone or in combination of two or more.

  The blending amount of zinc oxide is preferably in the range of 3 to 7 parts by mass per 100 parts by mass of component (A). If the amount is less than 3 parts by mass, the effect of improving processability is small, and if it exceeds 7 parts by mass, the appearance may be deteriorated. A more preferable range of the blending amount of zinc oxide is 4 to 6 parts by mass per 100 parts by mass of the component (A).

  As the vulcanizing agent of component (F), an organic peroxide is preferable. Examples of organic peroxides include dicumyl peroxide, 1,3-bis (tert-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane, di-tert. -Butyl peroxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexyne-3, 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane, n -Butyl-4,4-bis (tert-butylperoxy) valerate, benzoyl oxide, 2,4-dichlorobenzoyl peroxide, tert-butylperoxybenzoate, tert-butylperoxyisopropyl carbonate, diacetyl peroxide, lauroylper Oxide, tert-butyl kumi Such as peroxide. These may be used individually by 1 type, and 2 or more types may be mixed and used for them. Among the vulcanizing agents, dicumyl peroxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane, 1,3-bis (tert-butylperoxy) are particularly preferred from the viewpoint of permanent elongation characteristics. Isopropyl) benzene is preferred. The organic peroxide is preferably blended in an amount of 2 to 6 parts by mass, more preferably 2 to 4 parts by mass with respect to 100 parts by mass of the component (A). If the blending amount is less than 2 parts by mass, the permanent elongation characteristics may be deteriorated. Moreover, when a compounding quantity exceeds 8 mass parts, a softness | flexibility falls and there exists a possibility that prior diameter expansion at the time of mounting | wearing a cable connection part with a normal temperature shrinkable tube may become difficult.

  In addition, when using an organic peroxide as a vulcanizing agent, it is possible to further improve the trauma resistance and the stress relaxation property by adding a vulcanization aid. Examples of the vulcanization aid include zinc acrylate or a salt thereof, zinc methacrylate or a salt thereof, ethylene glycol dimethacrylate, N, N′-m-phenylene dimaleimide, triallyl isocyanurate, polyfunctional methacrylate monomer, and the like. Is mentioned. The compounding quantity of a vulcanization adjuvant is 1.0-5.0 mass parts normally with respect to 100 mass parts of (A) component, for example in zinc methacrylate or its salt, Preferably, it is 2.0-4. 0 parts by mass. Moreover, in N, N'-m-phenylene dimaleimide, it is 0.4-2.2 mass parts normally with respect to 100 mass parts of polymer components, Preferably, it is 0.8-1.7 mass parts. If the blending amount is less than the above range, the effect of addition cannot be sufficiently obtained, and if it exceeds the above range, flexibility may be lowered.

  Addition of antioxidants, lubricants, processing aids, colorants, flame retardants, anti-aging agents, UV absorbers, plasticizers, etc. An agent can be mix | blended in the range which does not inhibit the effect of this invention.

  Examples of the antioxidant include 2-mercaptobenzimidazole, and examples of the lubricant include fatty acid such as stearic acid, fatty acid ester such as n-butyl stearate, fatty acid metal salt such as fatty acid calcium salt, fatty acid ester and fatty acid metal. And a mixture of salts. Examples of processing aids include polyethylene glycol and triethanolamine.

  The cold-shrinkable tube of the present invention is obtained by uniformly mixing the above components using a kneader or the like to obtain a rubber compound, which is extruded into a tube shape and then vulcanized by a conventional method. The blending method of each component when obtaining a rubber compound is not particularly limited, and a blending component other than a vulcanizing component such as a vulcanizing agent and a vulcanizing auxiliary is kneaded in advance to form a master batch, and the remaining components are added. Any of a method of further kneading, a method of adding and kneading the respective components in an arbitrary order, a method of adding all of the components simultaneously and kneading may be used.

  The cold-shrinkable tube obtained in this way is flexible and excellent in workability, has good permanent elongation characteristics and stress relaxation characteristics, has excellent trauma resistance, has good insulating properties, and has excellent surface smoothness. Yes. Therefore, a highly reliable cable connection part can be formed using this.

In addition, as for the composition used for formation of the normal temperature shrinkable tube of this invention, it is preferable that (i) Mooney viscosity ML1 _{+ 4} (100 degreeC) is 20-40, and it is more preferable that it is 25-35. When the Mooney viscosity ML _{1 + 4} (100 ° C.) is less than 20, it is difficult to maintain the shape of the extruded product. When the Mooney viscosity ML _{1 + 4} (100 ° C.) exceeds 40, the extrusion processability is deteriorated and the surface smoothness is poor.
Mooney viscosity ML _{1 + 4} (100 ° C.) conforms to JIS K 6300-1 (Unvulcanized rubber—physical properties—Part 1: Determination of viscosity and scorch time using Mooney viscometer) for the composition before crosslinking. Measured.

Moreover, it is preferable that the composition used for formation of the normal temperature shrinkable tube of the present invention has (ii) durometer hardness of 30 to 60, and more preferably 40 to 48. If the durometer hardness is less than 30, deformation easily occurs when a load is applied to the molded product. If the durometer hardness exceeds 60, pre-expansion when attaching a cold-shrinkable tube to a cable becomes difficult.
The durometer hardness is measured by a type A durometer of JIS K 6253-3 (vulcanized rubber and thermoplastic rubber—how to obtain hardness).

The composition used for forming the cold-shrinkable tube of the present invention preferably has (iii) a tensile strength of 7 MPa or more, (iv) a tensile elongation of 600% or more, and (iii) a tensile strength. More preferably, it is 9 to 11 MPa and (iv) the tensile elongation is 600 to 700%. If the tensile strength is less than 7 MPa or the tensile elongation is less than 600%, the cold-shrinkable tube tends to break during diameter expansion.
The tensile strength and tensile elongation are measured in accordance with JIS K 6251 (vulcanized rubber and thermoplastic rubber—how to obtain tensile properties).

Moreover, the composition used for forming the cold-shrinkable tube of the present invention preferably has (v) permanent elongation of 15% or less, more preferably 5 to 15%, and even more preferably 7 to 12%. If the permanent elongation exceeds 15%, the adhesiveness to the mounted surface after the inner core is pulled out decreases.
Permanent elongation is measured in accordance with JIS K 6273 (vulcanized rubber and thermoplastic rubber-how to determine tensile permanent strain, elongation rate and creep rate).

The composition used for forming the cold-shrinkable tube of the present invention preferably has (vi) a volume resistivity of 1 × 10 ¹² Ω · cm or more, preferably 2 × 10 ¹² Ω · cm or more. Is more preferable. When the volume resistivity is less than 1 × 10 ¹² Ω · cm, it becomes difficult to use as an insulating coating.
The volume resistivity is measured in accordance with JIS K 6271-1 (vulcanized rubber and thermoplastic rubber-how to obtain electrical resistivity-part 1: double ring electrode method).

  Next, the cable connection part using the cold shrinkable tube of the present invention will be described.

  FIG. 1 is a longitudinal sectional view showing an example of a cable connecting portion using the cold shrinkable tube of the present invention. This example is an example in which the cold shrinkable tube of the present invention is used as a waterproof protective tube for a cable connection portion.

  In FIG. 1, reference numeral 1 indicates a pair of power cables to be connected. Each of these power cables 1, 1 is stepped off, and the cable conductor 2 and the cable insulator 3 are exposed, respectively. The cable conductors 2 are connected to each other by a conductor connecting pipe 4, and an insulating cylinder 5 is mounted on the conductor connecting pipe 4 across the cable insulators 3 and 3. The insulating cylinder 5 has a structure in which an inner electrode 5a and an outer electrode 5c having semiconductivity are provided on the inner peripheral surface and the outer peripheral surface of an insulating cylinder main body 5b having insulating properties, respectively. A braided mesh 6 is provided outside the insulating cylinder 5, and a room temperature shrinkable tube 7 of the present invention is attached so as to cover the braided mesh 6.

  Prior to use, the cold shrink tube 7 is inserted with a cylindrical expanded holding member called an inner core to maintain the expanded diameter, and the cable is passed through and placed at a predetermined position. It is attached by removing. By pulling out the support material, the cold shrink tube 7 is reduced in diameter and fixed at a predetermined position.

  An insulating tape 9 is wound around the cable 1 (cable sheath 8) at both ends of the cold shrink tube 7, and a semi-conductive layer such as an ACP tape is formed on the cable outer semiconductive layer (not shown). A conductive fusion tape 10 is wound.

  In the cable connecting portion configured as described above, as a waterproof protective tube, (B) 40 to 70 parts by mass of carbon black and (B) 100 parts by mass of ethylene / propylene / diene terpolymer, and ( C) Since a normal temperature shrinkable tube made of a crosslinked product of a composition containing 30 to 40 parts by mass of calcined clay is used, the appearance is good and excellent waterproof properties can be provided.

  In addition, although the said embodiment is an example of the intermediate connection part which used the normal temperature shrinkable tube of this invention as a waterproofing protection tube, this invention is not limited to such an example, It mounts | wears on a conductor connection pipe | tube. It can also be used as an insulation reinforcing tube. Further, the connecting portion is not limited to the intermediate connecting portion, and can be applied to a cable terminal portion or the like. When used as an insulating reinforcing tube, a highly reliable insulating reinforcing body can be formed.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples at all. In addition, the component used by the Example and the comparative example is as follows. The diene species of EPDM is 5-ethylidene-2-norbornene, and the Mooney viscosity of EPDM is a value measured according to ASTM D 1646. The extension oil used in the oil-extended EPDM is a paraffinic process oil.

EPDM (ethylene / propylene / diene terpolymer) (1):
Ethylene content 51% by weight, diene content 3.5% by weight,
Mooney viscosity ML _{1 + 4} (125 ° C.) 81
EPDM (ethylene / propylene / diene terpolymer) (2):
Ethylene content 59% by weight, diene content 3.5% by weight,
Mooney viscosity ML _{1 + 4} (125 ° C.) 73, oil extended amount 70 phr
Carbon black: good extrudability furnace carbon black (FEF)
Average particle size 43 nm, iodine adsorption 44 mg / g,
DBP absorption 115cm ³ / 100g
Firing clay: vinylsilane coupling agent surface-treated calcining clay Average particle size 1.4 μm
Process oil: Paraffinic process oil Zinc oxide: Two types of zinc oxide Organic peroxide: 1,3-bis (tert-butylperoxyisopropyl) benzene

Example 1
70 parts by mass of EPDM (1), 30 parts by mass of EPDM (2) (as polymer component amount), 60 parts by mass of carbon black, 40 parts by mass of calcined clay, 59 parts by mass of process oil, 5 parts by mass of zinc oxide, and organic peroxide After kneading 2.5 parts by mass uniformly with a kneader, it was extruded into a tube shape and heated and vulcanized at 0.6 MPa and 180 ° C. for 80 minutes to obtain a room temperature with an outer diameter of 37 mm, a length of 670 mm, and a wall thickness of 4.5 mm. A shrink tube was prepared. Separately, the kneaded product was extruded into a sheet shape with an 8-inch roll and subjected to press molding vulcanization at 170 ° C. for 25 minutes to prepare a 2 mm thick sheet.

(Examples 2 and 3, Comparative Examples 1 to 4)
In the same manner as in Example 1, the components shown in Table 1 were used in the amounts shown in Table 1 to prepare cold-shrinkable tubes and sheets.

  About the sheet | seat obtained by each Example and each comparative example, durometer hardness, tensile strength, tensile elongation, permanent elongation, and volume resistivity were measured. The kneaded product before vulcanization was measured for Mooney viscosity and evaluated for extrudability. The measurement method and evaluation method are as follows.

[Mooney viscosity]
Measured based on JIS K 6300-1 (unvulcanized rubber—physical properties—part 1: how to determine viscosity and scorch time using Mooney viscometer).
[Durometer hardness]
It was measured with a type A durometer defined in JIS K 6253-3 (vulcanized rubber and thermoplastic rubber—how to obtain hardness).
[Tensile strength, tensile elongation]
Based on JIS K 6251 (vulcanized rubber and thermoplastic rubber—how to obtain tensile properties), measurement was performed using a No. 3 dumbbell test piece.
[Permanent elongation]
In a 70 ° C. thermostatic chamber with a strip-shaped test piece having a width of 5 mm as defined in JIS K 6273 (vulcanized rubber and thermoplastic rubber-how to obtain tensile permanent strain, elongation rate and creep rate) stretched 200%. After holding for 24 hours, it was opened, and the distance between marked lines 30 minutes after opening was measured, and the rate of change in the distance between marked lines after elongation relative to the distance between marked lines before elongation was determined.
[Volume resistivity]
The measurement was performed according to JIS K 6271-1 (vulcanized rubber and thermoplastic rubber—how to obtain electrical resistivity—part 1: double ring electrode method).
[Extrudability I (Die Swell)]
In accordance with ASTM D2230, the appearance (continuity and sharpness) of the edge portion of the extrudate with a garbage die was observed and evaluated according to the following criteria.
◎: Almost does not swell during extrusion ○: Slightly swells during extrusion △: Swells during extrusion ×: Swells greatly during extrusion [extrusion processability II (surface smoothness)]
Similar to the extrudability I, the extrudate by the garbage die was observed according to ASTM D2230 and evaluated according to the following criteria.
A: Very good (the whole surface is smooth)
○: Good (there is a slightly rough surface)
Δ: Slightly defective (slightly large roughness is partially recognized)
X: Defect (Roughness is recognized on the entire surface)

  These results are shown in the lower column of Table 1.

  As apparent from Table 1, Examples 1 to 3 are all indices of Mooney viscosity and durometer hardness, which are workability indices, tensile strength and tensile elongation, which are indices of mechanical properties, and room temperature shrinkage. Good results were obtained for permanent elongation, volume resistivity as an index of insulation, and extrusion processability.

  Insulating cold-shrinkable tube for cable connection part of the present invention has improved surface smoothness while maintaining the conventional excellent characteristics such as permanent elongation characteristic, stress relaxation characteristic insulation, etc. It is useful as an insulating cold shrink tube to be attached.

  DESCRIPTION OF SYMBOLS 1 ... Electric power cable, 2 ... Cable conductor, 3 ... Cable insulator, 4 ... Conductor connection pipe, 5 ... Insulation cylinder, 6 ... Braided mesh, 7 ... Cold shrink tube, 8 ... Cable sheath, 9 ... Insulation tape, 10 ... Semi-conductive fusing tape.

Claims (8)

  (A) A crosslinked product of a composition containing 50 to 70 parts by mass of carbon black and (C) 30 to 40 parts by mass of calcined clay with respect to 100 parts by mass of an ethylene / propylene / diene terpolymer. An insulating cold-shrinkable tube for cable connection, characterized by comprising:   The said composition contains 80-100 mass parts in total of (B) component and (C) component with respect to 100 mass parts of (A) component, The insulation for cable connection parts of Claim 1 characterized by the above-mentioned. Cold shrink tube. Component (A) is: (a-1) ethylene / propylene / diene terpolymer 60 having an ethylene content of 50 to 60 mass%, a diene content of 3 to 5 mass%, and a Mooney viscosity ML _{1 + 4} (125 ° C.) of 60 to 90. -80% by mass, and (a-2) an ethylene / propylene / diene terpolymer having an ethylene content of 40 to 70% by mass, a diene content of 3 to 6% by mass, and a Mooney viscosity ML _{1 + 4} (125 ° C.) of 120 or more. The insulating normal temperature shrinkable tube for a cable connection part according to claim 1 or 2, wherein the tube comprises 40% by mass. The composition comprises (i) Mooney viscosity ML _{1 + 4} (100 ° C.) 20-40, (ii) durometer hardness 30-60, (iii) tensile strength 7 MPa or more, (iv) tensile elongation 600% or more, (v 4. The insulating room temperature shrinkable tube for cable connection according to claim 1, which has a permanent elongation of 15% or less and (vi) a volume resistivity of 1 × 10 ¹² Ω · cm or more.   The cable connection part according to any one of claims 1 to 4, wherein the composition further comprises (D) 60 to 100 parts by mass of process oil with respect to 100 parts by mass of the component (A). Insulating cold shrink tube. Component (B) has an average particle diameter of 40 to 60 nm, any of claims 1 to 5, characterized in that the carbon black iodine adsorption 30 to 50 mg / g, DBP absorption amount 100~120cm ³ / 100g 1 Insulating cold-shrinkable tube for cable connection part as described in the section.   (C) Component is the baking silica surface-treated with the silane coupling agent, The insulation normal temperature shrinkable tube for cable connection parts of any one of Claim 1 thru | or 6 characterized by the above-mentioned.   A cable connecting part comprising the insulating cold shrink tube for a cable connecting part according to any one of claims 1 to 7.

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