Resin composition, crosslinked body, wire / cable and method for manufacturing the same

Abstract

To provide a resin composition from which a crosslinked body that is excellent in heat resistance and handleability is improved can be given, and a crosslinked body, a wire / cable and a method for manufacturing the same.SOLUTION: A resin composition contains ethylene propylene rubber, polyethylene, a silane compound, a free radical generation compound and a silanol condensation catalyst, wherein a content of the polyethylene is 30 to 50 pts.wt. with respect to 100 pts.wt. of the ethylene propylene rubber, the melting point of the polyethylene is 123 to 135°C, a content of the silane compound is 0.8 to 1.2 pts.wt. with respect to 100 pts.wt. of the ethylene propylene rubber, a content of the free radical generation compound is 0.03 to 0.08 pts.wt. with respect to 100 pts.wt. of the ethylene propylene rubber, and a content of the silanol condensation catalyst is 0.05 to 0.20 pt.wt. with respect to 100 pts.wt. of the ethylene propylene rubber.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a resin composition, a crosslinked product, an electric wire / cable, and a method for producing the same. [Background technology]

[0002] In recent years, interest in environmental issues has grown worldwide, and wires and cables that use halogen-free compositions that do not generate harmful halogen gases when incinerated are becoming more common. Various proposals have also been made for wires and cables that use halogen-free compositions.

[0003] As halogen-free compositions for use in electric wires and cables, compositions containing polyolefin resins are known, and various compositions have been proposed. For example, Patent Document 1 below proposes a silane-crosslinkable insulating composition containing a polyolefin, a silane compound, a free radical-generating compound, and a silanol condensation catalyst.

[0004] On the other hand, when a composition is crosslinked using a silane compound, the degree of crosslinking tends to be low, resulting in problems such as reduced heat resistance and poor handleability due to stickiness. Generally, the degree of crosslinking in silane crosslinking is lower than that of chemical crosslinking (peroxide, sulfur, etc.) and electron beam crosslinking, and in order to increase the degree of crosslinking, a large amount of additives must be added, resulting in problems in terms of material cost and productivity. Regarding stickiness, for example, in the silane-crosslinkable insulating composition described in Patent Document 1 below, it was actually necessary to suppress stickiness by adding talc, a filler, in approximately the same amount as the polyolefin. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-70611 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a resin composition capable of giving a crosslinked product having excellent heat resistance and improved handleability, as well as a crosslinked product, an electric wire / cable, and a method for producing the same. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the resin composition according to the present invention has the following characteristics.

[0008] Contains ethylene-propylene rubber, polyethylene, silane compounds, free radical generating compounds and silanol condensation catalysts. the content of the polyethylene is 30 to 50 parts by weight based on 100 parts by weight of the ethylene-propylene rubber, The melting point of the polyethylene is 123 to 135°C, the content of the silane compound is 0.8 to 1.2 parts by weight based on 100 parts by weight of the ethylene-propylene rubber, The content of the free radical generating compound is 0.03 to 0.08 parts by weight based on 100 parts by weight of the ethylene-propylene rubber, The content of the silanol condensation catalyst is 0.05 to 0.20 parts by weight based on 100 parts by weight of the ethylene-propylene rubber. It is a resin composition. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a resin composition capable of giving a crosslinked product having excellent heat resistance and improved handleability, as well as a crosslinked product, an electric wire / cable, and a method for producing the same.

[0010] The present invention has been briefly described above. The details of the present invention will become clearer by reading the following detailed description of the invention (hereinafter also referred to as "embodiments") with reference to the accompanying drawings. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view of an electric wire / cable according to this embodiment, where (a) is a cross-sectional view of an electric wire, and (b) is a cross-sectional view of a cable. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, one embodiment of the resin composition according to the present embodiment, as well as the electric wire / cable and the method for producing the same will be described with reference to the drawings.

[0013] FIG. 1 is a cross-sectional view of an electric wire / cable according to this embodiment, where (a) is a cross-sectional view of an electric wire, and (b) is a cross-sectional view of a cable. As shown in FIG. 1( a ), the electric wire 1 of this embodiment includes a conductor 2 such as a copper wire, an insulator 3 covering the outer periphery of the conductor 2 , and a covering layer 4 covering the outer periphery of the insulator 3 . As shown in FIG. 1(b), the cable 10 according to this embodiment includes a plurality of bundled electric wires 1 (1a, 1b, 1c) and a covering layer 4 that covers the periphery of the bundled electric wires 1.

[0014] The conductor 2 may be a single wire or a bundle of multiple wires. Examples of materials that can be used for the conductor 2 include conductive metals such as copper, plated copper, copper alloys, aluminum, and aluminum alloys.

[0015] The insulator 3 is made of a crosslinked product of the resin composition according to this embodiment. The resin composition according to this embodiment contains at least ethylene-propylene rubber and polyethylene as base resins, and has the following composition and physical properties.

[0016] <Resin composition> The resin composition according to the present embodiment contains an ethylene-propylene rubber, polyethylene, a silane compound, a free radical-generating compound, and a silanol condensation catalyst, wherein the content of the polyethylene is 30 to 50 parts by weight per 100 parts by weight of the ethylene-propylene rubber, the melting point of the polyethylene is 123 to 135°C, the content of the silane compound is 0.8 to 1.2 parts by weight per 100 parts by weight of the ethylene-propylene rubber, the content of the free radical-generating compound is 0.03 to 0.08 parts by weight per 100 parts by weight of the ethylene-propylene rubber, and the content of the silanol condensation catalyst is 0.05 to 0.20 parts by weight per 100 parts by weight of the ethylene-propylene rubber. The resin composition according to this embodiment can also be referred to as a silane-crosslinkable resin composition.

[0017] [Ethylene-propylene rubber] The resin composition according to this embodiment contains ethylene-propylene rubber.

[0018] In this specification, ethylene-propylene rubber refers to both EPDM (ethylene-propylene-diene copolymer), which is a terpolymer of ethylene, propylene, and a non-conjugated diene, and EPM (ethylene-propylene rubber), which is a copolymer of ethylene and propylene.

[0019] In this embodiment, the diene component in the EPDM is not particularly limited, but examples thereof include dicyclopentadiene (DCPD), 5-ethylidene-2-norbornene (ENB), vinylidene norbornene (VNB), and 1,4-hexadiene (HD or 1,4-HD). These diene components may be contained alone or in combination of two or more.

[0020] [polyethylene] The resin composition according to this embodiment contains polyethylene.

[0021] In the present embodiment, polyethylene that can be used is not particularly limited, but examples thereof include high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and very-low-density polyethylene (VLDPE). These polyethylenes may be used alone or in combination of two or more. From the viewpoint of heat deformation resistance, it is preferable to use at least one polyethylene selected from the group consisting of LLDPE and HDPE.

[0022] The content of polyethylene in the resin composition according to this embodiment is 30 to 50 parts by weight, and particularly preferably 32 to 38 parts by weight, per 100 parts by weight of the ethylene-propylene rubber. If the polyethylene content is less than 30 parts by weight per 100 parts by weight of ethylene-propylene rubber, the deformation characteristics of the crosslinked resin composition when heated may decrease, which may result in a decrease in production efficiency. On the other hand, if the content exceeds 50 parts by weight, the hardness of the crosslinked resin composition may increase, which may impair the flexibility characteristic of rubber.

[0023] In this embodiment, the melting point of the polyethylene is 123 to 135°C, and particularly preferably 125 to 130°C. If the melting point of the polyethylene is less than 123°C, the resistance to deformation of the crosslinked resin composition when heated may decrease, possibly resulting in a ground fault when an electric current is applied, whereas if the melting point exceeds 135°C, the hardness of the crosslinked resin composition may increase, possibly impairing the flexibility inherent to rubber.

[0024] In the present embodiment, the density of the polyethylene measured in accordance with JIS K 7112 is not particularly limited, but is preferably 0.923 to 0.945 g / cm. 3 is preferable, and 0.930 to 0.940 g / cm 3 is particularly preferred.

[0025] [Silane compounds] The resin composition according to this embodiment contains a silane compound.

[0026] In the present embodiment, the silane compound that can be used is not particularly limited, and examples thereof include vinyl silane compounds such as vinyl trimethoxysilane, vinyl triethoxysilane, and vinyl tris(β-methoxysilane); amino silane compounds such as γ-aminopropyl trimethoxysilane, γ-aminopropyl triethoxysilane, N-β-(aminoethyl)γ-aminopropyl trimethoxysilane, β-(aminoethyl)γ-aminopropyl methyldimethoxysilane, and N-phenyl-γ-aminopropyl trimethoxysilane; and β-(3,4-epoxy Examples of suitable silane compounds include epoxysilane compounds such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and the like; acrylic silane compounds such as γ-methacryloxypropyltrimethoxysilane, and the like; polysulfide silane compounds such as bis(3-(triethoxysilyl)propyl)disulfide and bis(3-(triethoxysilyl)propyl)tetrasulfide, and the like; and mercaptosilane compounds such as 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane. These silane compounds may be used alone or in combination of two or more. In view of reactivity with EPDM and polyethylene, it is preferable to use vinyltrimethoxysilane as the silane compound.

[0027] The content of the silane compound in the resin composition according to this embodiment is 0.8 to 1.2 parts by weight, and particularly preferably 0.9 to 1.1 parts by weight, per 100 parts by weight of the ethylene-propylene rubber. If the content of the silane compound per 100 parts by weight of ethylene-propylene rubber is less than 0.8 parts by weight, the degree of crosslinking of the crosslinked body of the resin composition will be low, the deformation resistance of the crosslinked body when heated will be reduced, and there is a risk of ground faults when electricity is applied. On the other hand, if the content exceeds 1.2 parts by weight, not only will the production costs be increased, but the crosslinking reaction of the resin composition will proceed in the extruder, causing appearance defects such as the formation of protrusions on the product surface, which may reduce the productivity of electric wires and cables.

[0028] [Free radical-generating compounds] The resin composition according to this embodiment contains a free radical-generating compound.

[0029] In the present embodiment, the free radical-generating compound that can be used is not particularly limited, and examples thereof include organic peroxides such as dicumyl peroxide, tert-butylcumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexyne-3, 1,3-bis(tert-butylperoxyisopropyl)benzene, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, n-butyl-4,4-bis(tert-butylperoxy)valerate, benzoyl oxide, 2,4-dichlorobenzoyl peroxide, tert-butyl peroxybenzoate, tert-butylperoxyisopropyl carbonate, diacetyl peroxide, and lauroyl peroxide. These free radical-generating compounds may be used alone or in combination of two or more. In view of reactivity with EPDM and polyethylene, it is preferred to use dicumyl peroxide as the free radical generating compound.

[0030] The content of the free radical-generating compound in the resin composition according to this embodiment is 0.03 to 0.08 parts by weight, and particularly preferably 0.04 to 0.06 parts by weight, per 100 parts by weight of the ethylene-propylene rubber. If the content of the free radical-generating compound per 100 parts by weight of ethylene-propylene rubber is less than 0.03 parts by weight, the degree of crosslinking of the crosslinked resin composition may be low, and the heat distortion resistance may be reduced. On the other hand, if the content exceeds 0.08 parts by weight, not only may the production cost increase, but the crosslinking reaction of the resin composition may proceed in the extruder, resulting in poor appearance such as the formation of protrusions on the product surface, which may reduce the productivity of electric wires and cables.

[0031] [Silanol condensation catalyst] The resin composition according to this embodiment contains a silanol condensation catalyst.

[0032] In the present embodiment, the silanol condensation catalyst that can be used is not particularly limited, but for example, dibutyltin dilaurate, dibutyltin dimaleate, stannous acetate, dibutyltin diacetate, dibutyltin dioctoate, dibutyltin methylcapsid, dioctyltin dilaurate, dioctyltin dimaleate, dioctyltin diacetate, dioctyltin dioctoate, dioctyltin methylcapsid, lead naphthenate, zinc caprylate, cobalt naphthenate, tetrabutyl titanate, lead stearate, zinc stearate, cadmium stearate, barium stearate, calcium stearate.These silanol condensation catalysts can be used alone or in combination of two or more. From the viewpoint of the efficiency of the crosslinking reaction of the resin composition, it is preferable to use dioctyltin dilaurate as the silanol condensation catalyst.

[0033] The content of the silanol condensation catalyst in the resin composition according to this embodiment is 0.05 to 0.20 parts by weight, and particularly preferably 0.08 to 0.12 parts by weight, per 100 parts by weight of the ethylene-propylene rubber. If the content of silanol condensation catalyst per 100 parts by weight of ethylene-propylene rubber is less than 0.05 parts by weight, the degree of crosslinking of the crosslinked resin composition may be low, and heat distortion resistance may be reduced. On the other hand, if the content exceeds 0.20 parts by weight, not only may production costs increase, but the crosslinking reaction of the resin composition may proceed in the extruder, resulting in poor appearance such as the formation of protrusions on the product surface, which may reduce productivity of electric wires and cables.

[0034] [Other ingredients] The resin composition according to the present embodiment may contain other components in addition to the above components. The other components are not particularly limited, but examples thereof include crosslinking aids, fillers, lubricants, antioxidants, processing aids, UV absorbers, pigments, antistatic agents, and dispersants.

[0035] The crosslinking aid is not particularly limited, but examples thereof include compounds having two or more double bonds in the molecule, and specific examples thereof include diacrylates such as 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, tripropylene glycol diacrylate, and polypropylene glycol diacrylate; 1,3-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, and Examples of the acrylate include dimethacrylates such as acrylates and polyethylene glycol dimethacrylate; triacrylates such as trimethylolpropane triacrylate, tetramethylolmethane triacrylate, and pentaerythritol triacrylate; trimethacrylates such as trimethylolpropane trimethacrylate and trimethylolethane trimethacrylate; tetraacrylates such as pentaerythritol tetraacrylate and tetramethylolmethane tetraacrylate; divinyl aromatic compounds such as divinylbenzene; cyanurates such as triallyl cyanurate and triallyl isocyanurate; diallyl compounds such as diallyl phthalate; and triallyl compounds. Among these, a preferred crosslinking aid is triethylene glycol dimethacrylate.

[0036] The filler is not particularly limited, but examples thereof include organic bromine-containing flame retardants such as brominated ethylene bisphthalimide derivatives, bisbrominated phenyl terephthalamide derivatives, brominated bisphenol derivatives, and 1,2-bis(bromophenyl)ethane; inorganic flame retardants such as magnesium hydroxide and aluminum hydroxide; phosphate-based flame retardants such as aromatic condensed phosphate esters, ammonium polyphosphate, and melamine phosphate; intumescent flame retardants such as ammonium polyphosphate, melamine polyphosphate, piperazine polyphosphate, ammonium pyrophosphate, melamine pyrophosphate, and piperazine pyrophosphate; light calcium carbonate, heavy calcium carbonate, mica, bentonite, zeolite, slaked lime, kaolin, talc, and diatomaceous earth.

[0037] The lubricant is not particularly limited, but examples thereof include hydrocarbon-based lubricants, fatty acid-based lubricants, and ester-based lubricants.

[0038] The antioxidant is not particularly limited, but examples thereof include phenol-based antioxidants, amine-based antioxidants, and phosphorus-based antioxidants.

[0039] Processing aids are not particularly limited, but examples thereof include petroleum oils such as paraffinic oils, aromatic oils, and naphthenic oils.

[0040] The ultraviolet absorber is not particularly limited, but examples thereof include benzophenone compounds, benzotriazole compounds, salicylate compounds, substituted tolyl compounds, and metal chelate compounds.

[0041] The pigment is not particularly limited, but general inorganic pigments and organic pigments listed in the "Pigment Handbook (compiled by the Japan Pigment Technology Association)" can be used. Examples of inorganic pigments include titanium-containing (composite) metal oxides such as titanium yellow, zinc oxide, iron oxide, zinc sulfide, and antimony trioxide. Examples of organic pigments include phthalocyanine-based, anthraquinone-based, quinacridone-based, azo-based, isoindolinone-based, quinophthalone-based, perinone-based, and perylene-based pigments.

[0042] The antistatic agent is not particularly limited, but examples thereof include alkyl phosphate esters and silicic acid compounds.

[0043] The dispersant is not particularly limited, but examples thereof include acrylic dispersants, fatty acid ester dispersants, polyethylene glycol dispersants, nonionic surfactants, amphiphilic triphenylene derivatives, and pyrene derivatives.

[0044] The resin composition according to this embodiment may or may not contain other components. In the present embodiment, when the resin composition contains other components, the content thereof is not particularly limited, but is preferably 1.0 to 30 parts by weight, and particularly preferably 1.0 to 10.0 parts by weight, per 100 parts by weight of the ethylene-propylene rubber.

[0045] Furthermore, the resin composition according to this embodiment can provide a crosslinked product with improved handleability without containing a filler such as talc. In this embodiment, the resin composition does not contain a filler, or the content of the filler relative to 100 parts by weight of the ethylene-propylene rubber can be, for example, 1.0 to 30.0 parts by weight. Alternatively, in this embodiment, the resin composition does not contain talc, or the content of talc relative to 100 parts by weight of the ethylene-propylene rubber can be, for example, 1.0 to 20.0 parts by weight.

[0046] <Crosslinked body> The crosslinked body according to this embodiment is obtained by crosslinking the above-described resin composition. The method for crosslinking the resin composition is not particularly limited, but for example, a method in which the resin composition is extruded at a temperature in the range of 180 to 240°C can be mentioned. Furthermore, in the resin composition according to this embodiment, crosslinking gradually progresses over time due to a silanol condensation reaction in the presence of moisture. Taking advantage of this, the resin composition can be immersed in warm water after extrusion molding to promote crosslinking. For example, crosslinking can be promoted by immersing the resin composition after extrusion molding in warm water at 90°C for one day.

[0047] In this embodiment, the degree of crosslinking of the crosslinked body measured in accordance with JIS C 3005 is not particularly limited, but is preferably 20 to 60%, and particularly preferably 30 to 50%. A crosslinking degree of 20% or more of the crosslinked product is preferable because it improves heat resistance, and a crosslinking degree of 60% or less is preferable because it suppresses scorching (premature crosslinking) in the extruder and improves long-term continuous extrudability.

[0048] The degree of crosslinking is measured in accordance with JIS C 3005, more specifically, Section 25 of JIS C 3005:2014. Specifically, a 5g sample of the crosslinked material is prepared and immersed in 100g of xylene, which is kept at 120°C for 24 hours. The sample is then removed from the solvent and placed in a vacuum desiccator. It is then dried at 100±2°C and at a vacuum of 1.3kPa (10 Torr) or less for at least 24 hours. After drying, the weight of the sample (post-test weight) is measured to the nearest milligram and expressed as a percentage compared to the sample's initial weight (pre-test weight).

[0049] In this embodiment, the JIS A hardness of the crosslinked body is not particularly limited, but is preferably not more than 80, and particularly preferably not more than 70. If the JIS A hardness of the crosslinked body is not more than 80, it is preferable because the flexibility is good. There is no particular lower limit for the JIS A hardness of the crosslinked product, but it can be, for example, 60 or more.

[0050] The JIS A hardness mentioned above means the Shore A hardness measured with a durometer type A in accordance with JIS K 6253 (2012).

[0051] <Wires and cables> The electric wire / cable according to this embodiment is an electric wire / cable in which the outer periphery of a conductor is covered with at least an insulator, and the insulator is made of the above-mentioned cross-linked body.

[0052] In this embodiment, the electric wire / cable (1, 10) can be provided with a coating layer 4 as shown in FIG. The coating layer 4 can be appropriately selected from known materials and is not particularly limited. For example, a foamable composition can be prepared by adding a foaming agent to the resin composition according to this embodiment and then foaming the foamed composition. Examples of foaming agents include known chemical decomposition foaming agents that generate carbon dioxide gas, nitrogen gas, or the like through chemical decomposition. Examples of the foaming agent include azo compounds such as azodicarbonamide (ADCA), nitroso compounds such as N,N'-dinitrosopentamethylenetetramine, hydrazine derivatives such as 4,4'-oxybis(benzenesulfonylhydrazide) (OBSH) and hydrazodicarbonamide (HDCA), and sodium bicarbonate. The amount of the foaming agent is preferably 0.1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, per 100 parts by weight of ethylene-propylene rubber.

[0053] Furthermore, various known additives such as fillers, lubricants, antioxidants, processing aids, UV absorbers, pigments, antistatic agents, and dispersants may be blended into the coating layer 4, as needed. Examples of these additives are as described above.

[0054] The manufacturing method according to this embodiment is a method for manufacturing an electric wire / cable (1, 10) in which the outer periphery of a conductor (2) is covered with at least an insulator (3), and includes the following steps (1) and (2). [1] A step of extruding the resin composition onto the outer periphery of the conductor (2). [2] A step of crosslinking the resin composition to form an insulator (3) made of a crosslinked body of the resin composition around the conductor (2).

[0055] More specifically, the manufacturing method according to this embodiment may include the following steps. [a] A step of mixing at least ethylene-propylene rubber, polyethylene, a silane compound, a free radical generating compound, a silanol condensation catalyst, and, if necessary, other components to prepare a resin composition. [b] A step of extruding the resin composition obtained in the step [a] and causing a graft reaction to form an insulator (3) made of a crosslinked body of the resin composition on the outer periphery of the conductor (2). [c] A step of forming a coating layer (4) on the outer periphery of the insulator (3) formed in the step [b].

[0056] In the step [a], the resin composition can be prepared by, for example, uniformly mixing at least ethylene-propylene rubber, polyethylene, a silane compound, a free radical-generating compound, a silanol condensation catalyst, and, if necessary, other components using a known mixing means. In the step [b], the method for extruding the resin composition is not particularly limited, and examples thereof include a method using a known extruder such as a single-screw extruder or a twin-screw extruder. The graft reaction in the step [b] is preferably carried out under conditions in which the resin temperature is 180 to 240°C. In the step [c], the coating layer 4 can be formed, for example, by using a known extruder such as a single-screw extruder or a twin-screw extruder to extrude the foamable composition around the insulator 3. During this extrusion step, the foamable composition foams to form the coating layer 4.

[0057] The insulator 3 of the electric wire / cable 1, 10 of this embodiment can be configured as a single layer or two or more layers. By configuring the insulator 3 as two or more layers and using a material with excellent appearance for the outer layer, an insulator with a smooth appearance can be formed. [Example]

[0058] The present embodiment will be further described below with reference to examples, but the present invention is not limited to the following examples.

[0059] The following materials were used: EPDM: Ethylene-propylene rubber, manufactured by Mitsui Chemicals, Inc., product name "3092PM" Polyethylene: L-LDPE (linear low-density polyethylene), manufactured by ENEOS NUC Corporation, product name "NUCG-5130", density (JIS K 7112 compliant) 0.924 g / cm 3 Silane compound: vinyltrimethoxysilane, manufactured by Evonik Japan Co., Ltd., trade name "DynasylanVTMO" Free radical generating compound: dicumyl peroxide, manufactured by Mitsui Fine Chemicals, Inc., trade name "DCP" Silanol condensation catalyst: dioctyltin dilaurate, manufactured by Nitto Kasei Co., Ltd., product name "U-810"

[0060] [Examples 1 to 5], [Comparative Examples 1 to 6] Various resin compositions were prepared according to the formulations shown in Tables 1 and 2. The obtained resin compositions were extrusion-molded, and the molded resin compositions were immersed in warm water at 90°C for one day to produce crosslinked bodies.

[0061] The heat deformation, degree of crosslinking, and hardness of the crosslinked products obtained from various resin compositions were measured by the methods described below, and the results were evaluated as follows. In addition, the cost and cable productivity were evaluated as follows.

[0062] Heat deformation (120°C x 20N): Measurement was performed by carrying out heat deformation in accordance with Section 4.23 of JIS C 3005:2014. The conditions for heat deformation were a heating temperature of 120°C and a deformation load of 20N. Heat deformation of 40% or less was judged as passing, and heat deformation of more than 40% was judged as failing. Degree of crosslinking: Measured in accordance with the test in Section 25 of JIS C 3005:2014. A degree of crosslinking between 20% and 60% was judged as passing, and a degree of crosslinking less than 20% or more than 60% was judged as failing.

[0063] Hardness (JIS A, 10-second value) Shore A hardness was measured using a durometer type A in accordance with JIS K6253 (2012). A 1 kg weight was placed on a press-molded, 2 mm thick, sheet-shaped cross-linked body, and the value measured by the hardness meter after 10 seconds was recorded. Hardness values ​​of 80 or less were judged to pass, and those above 80 were judged to fail. Cost and cable productivity: If the polyethylene content is less than 30 parts by weight, the resin composition will stick to the mixer when mixing, resulting in a lower product yield. Products with a product yield of 95% or more were rated A (pass), and those with a yield of less than 95% were rated B (fail). Furthermore, because the use of large amounts of silane compounds, free radical-generating compounds, and silanol condensation catalysts increases material costs, products with weight parts exceeding the appropriate range were rated B (fail).

[0064] The results are shown in Tables 1 and 2.

[0065] [Table 1]

[0066] [Table 2]

[0067] From the results in Tables 1 and 2, it was found that the resin compositions of Examples 1 to 5 gave crosslinked products or electric wires and cables that were excellent in heat resistance and had improved handling properties during production. In contrast, it was found that the crosslinked products or electric wires and cables obtained from the resin compositions of Comparative Examples 1 to 6 were inferior in at least one of heat resistance and handling properties.

[0068] It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be adopted within the scope of the present invention. For example, the present invention is not limited to the above-described embodiments, and modifications, improvements, etc. are possible as appropriate. In addition, the material, shape, dimensions, number, location, etc. of each component in the above-described embodiments are arbitrary and not limited as long as the present invention can be achieved.

[0069] Here, the features of the embodiments of the resin composition, crosslinked product, electric wire / cable and manufacturing method thereof according to the present invention will be briefly summarized and listed below in [1] to [7], respectively.

[0070] [1] Contains ethylene-propylene rubber, polyethylene, silane compounds, free radical generating compounds and silanol condensation catalysts. the content of the polyethylene is 30 to 50 parts by weight based on 100 parts by weight of the ethylene-propylene rubber, The melting point of the polyethylene is 123 to 135°C, the content of the silane compound is 0.8 to 1.2 parts by weight based on 100 parts by weight of the ethylene-propylene rubber, The content of the free radical generating compound is 0.03 to 0.08 parts by weight based on 100 parts by weight of the ethylene-propylene rubber, The content of the silanol condensation catalyst is 0.05 to 0.20 parts by weight based on 100 parts by weight of the ethylene-propylene rubber. Resin composition.

[0071] According to the resin composition of the above [1], the composition contains ethylene-propylene rubber, polyethylene, a silane compound, a free radical generating compound, and a silanol condensation catalyst, and the content and melting point of the polyethylene, as well as the contents of the silane compound, the free radical generating compound, and the silanol condensation catalyst are set within specific ranges. That is, the content of the polyethylene is 30 to 50 parts by weight per 100 parts by weight of the ethylene-propylene rubber, the melting point of the polyethylene is 123 to 135°C, the content of the silane compound is 0.8 to 1.2 parts by weight per 100 parts by weight of the ethylene-propylene rubber, the content of the free radical-generating compound is 0.03 to 0.08 part by weight per 100 parts by weight of the ethylene-propylene rubber, and the content of the silanol condensation catalyst is 0.05 to 0.20 part by weight per 100 parts by weight of the ethylene-propylene rubber. By satisfying all of these requirements, a crosslinked resin composition having excellent heat resistance and improved handling properties can be obtained.

[0072] [2] The resin composition according to [1] above, wherein the polyethylene is at least one selected from the group consisting of LLDPE (linear low-density polyethylene) and HDPE (high-density polyethylene).

[0073] According to the resin composition of the above configuration [2], since the polyethylene is specified, it is possible to provide a crosslinked resin composition having excellent resistance to heat deformation.

[0074] [3] The density of the polyethylene measured in accordance with JIS K 7112 is 0.923 to 0.945 g / cm 3 The resin composition according to the above [1],

[0075] According to the resin composition of the above configuration [3], since the density of the polyethylene is specified, it is possible to obtain a crosslinked resin composition having excellent mechanical properties.

[0076] [4] A crosslinked body obtained by crosslinking the resin composition according to any one of the above [1] to [3].

[0077] The crosslinked product having the above configuration [4] is obtained by crosslinking the resin composition according to any one of the above [1] to [3], and therefore has excellent heat resistance and improved handling properties.

[0078] [5] The crosslinked product according to [4] above, which has a degree of crosslinking measured in accordance with JIS C 3005 of 20 to 60%.

[0079] According to the crosslinked body having the above constitution [5], the range of the degree of crosslinking is specified, and therefore the crosslinked body has excellent heat resistance.

[0080] [6] An electric wire or cable in which the outer periphery of a conductor is covered with at least an insulator, the insulator comprising the crosslinked body according to [4] above.

[0081] According to the electric wire / cable having the configuration [6] above, since the insulator that covers at least the outer periphery of the conductor is made of the crosslinked body described in [4] above, the heat resistance is excellent and handling is improved.

[0082] [7] A method for producing an electric wire or cable in which the outer periphery of a conductor is covered with at least an insulator, the method comprising the following steps [1] to [2]: [1] A step of extruding the resin composition according to any one of [1] to [3] above onto the outer periphery of the conductor. [2] A step of crosslinking the resin composition to form an insulator made of a crosslinked body of the resin composition around the conductor.

[0083] The method for producing an electric wire or cable according to the above item [7] includes the steps of extruding the resin composition according to any one of the above items [1] to [3] onto the outer periphery of a conductor, and crosslinking the resin composition to form an insulator made of a crosslinked body of the resin composition on the outer periphery of the conductor. By employing such a production method, the obtained electric wire or cable has excellent heat resistance and improved handleability. [Explanation of symbols]

[0084] 1 electric wire 2 conductors 3. Insulators 4 Covering layer 10 Cable

Claims

1. Contains ethylene-propylene rubber, polyethylene, a silane compound, a free radical generating compound, and a silanol condensation catalyst; the content of the polyethylene is 30 to 50 parts by weight per 100 parts by weight of the ethylene-propylene rubber, The melting point of the polyethylene is 123 to 135°C, the content of the silane compound is 0.8 to 1.2 parts by weight based on 100 parts by weight of the ethylene-propylene rubber, the content of the free radical-generating compound is 0.03 to 0.08 parts by weight based on 100 parts by weight of the ethylene-propylene rubber; The content of the silanol condensation catalyst is 0.05 to 0.20 parts by weight based on 100 parts by weight of the ethylene-propylene rubber. Resin composition.

2. The resin composition according to claim 1, wherein the polyethylene is at least one selected from the group consisting of LLDPE (linear low density polyethylene) and HDPE (high density polyethylene).

3. The density of the polyethylene measured in accordance with JIS K 7112 is 0.923 to 0.945 g / cm ３ The resin composition according to claim 1,

4. A crosslinked body obtained by crosslinking the resin composition according to any one of claims 1 to 3.

5. The crosslinked body according to claim 4, having a degree of crosslinking of 20 to 60% as measured in accordance with JIS C 3005.

6. An electric wire / cable comprising a conductor and an outer periphery thereof covered with at least an insulator, the insulator comprising the crosslinked body according to claim 4.

7. A method for manufacturing an electric wire or cable in which the outer periphery of a conductor is covered with at least an insulator, the method comprising the following steps [1] to [2]: [1] A step of extruding the resin composition according to any one of claims 1 to 3 onto the outer periphery of the conductor. [2] A step of crosslinking the resin composition to form an insulator made of a crosslinked body of the resin composition around the conductor.

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