JP2019075240A - Manufacturing method of foamed polyolefin coated electric wire/cable and foamed polyolefin coated electric wire/cable - Google Patents

Abstract

To provide a manufacturing method of a foamed polyolefin coated electric wire/cable not only having excellent workability with improved easy tearability and strippability but also having sufficient mechanical characteristics and having good foamability and to provide a foamed polyolefin coated electric wire/cable.SOLUTION: The manufacturing method includes: a step of mixing at least 20 to 95 pts.wt. of a polyolefin-based resin and 5 to 80 pts.wt. of a rubber component based on 100 pts.wt. of a base resin with a crosslinking agent, a crosslinking auxiliary and a foaming agent to produce a polyolefin-based foamable resin composition; a step of crosslinking the polyolefin-based foamable resin composition to form a crosslinked body of the polyolefin-based foamable resin composition having a degree of crosslinking of 2 to 40% and a melt viscosity of 0.1 to 2.0 g/min as measured at 190°C and a load of 2.16 kgf; a step of extruding the resulting crosslinked body to form a coating layer comprising the crosslinked body around the outer periphery of a conductor; and a step of foaming the formed coating layer so as to have a foaming ratio of 3 to 30%.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a foamed polyolefin coated wire / cable and a foamed polyolefin coated wire / cable.

  In recent years, interest in environmental problems has been increasing worldwide, and cables and cables coated with a halogen-free composition that does not generate harmful halogen gas and the like during incineration are becoming widespread. In addition, various proposals have been made for wires and cables coated with a non-halogen composition.

  As a non-halogen composition used for coating of electric wire and cable, there is a polyolefin resin. So, in recent years, the halogen free flame retardant resin composition which mix | blended the metal hydroxide with the polyolefin resin as a flame retardant has come to be used abundantly. Also, conventionally, for the purpose of improving the tearability and peelability, there is known a technology in which a non-halogen flame retardant resin composition is made to contain a foaming agent and foamed at the time of production of a wire / cable.

  For example, in Patent Document 1 listed below, 20 to 80% by mass of ethylene / acrylic acid ester copolymer (a) and / or ethylene / vinyl acetate copolymer (b), 10 to 40% by mass of acrylic rubber (c), And acrylic acid-modified polyolefin (d) in an amount of 10 to 40% by mass and, if necessary, up to 20% by mass or less of polyethylene (e) and / or styrene block copolymer modified with unsaturated carboxylic acid or its derivative (F) A crosslinked product of a composition containing 150 to 250 parts by mass of metal hydrate (g) surface-treated with a silane coupling agent relative to 100 parts by mass of a resin mixture containing 20% by mass or less Insulated wires that are coated have been proposed.

  Patent Document 2 below uses a resin composition obtained by adding a non-halogen flame retardant such as magnesium hydroxide to a mixture of a polyolefin resin and polyphenylene ether as a base polymer, and uses chemical foam extrusion and gas foaming. There has been proposed a shielded wire in which an insulating layer is formed by foam extrusion by an extrusion method.

JP 2001-325833 A JP 2001-52537 A

  However, in Patent Document 1, it is necessary to mix a large amount of metal hydrate such as magnesium hydroxide in order to obtain the desired sufficient flame retardancy, the resin component becomes hard, and the wire / cable tears There is a problem that the ease and peelability deteriorate and the workability is inferior.

Moreover, in patent document 2, in order to improve heat resistance and chemical resistance, irradiation crosslinking of a foaming insulator is performed by methods, such as irradiating ionizing radiation, such as a gamma ray, but irradiation crosslinking is generally large In addition to the need for equipment, there is a problem that the production speed is low and the production efficiency is low.
In addition, as a method of crosslinking these resin compositions, silane crosslinking and the like are known as well. However, silane crosslinking is carried out immediately after extrusion because the resin composition is extruded after being extruded in a water tank or the like after extrusion. There is a problem that the melt viscosity is low and the foaming rate is not stable.

  The present invention has been made in view of the above-described circumstances, and its object is to have excellent foamability, excellent workability with improved tearability and peelability, and sufficient mechanical properties. It is an object of the present invention to provide a method for producing a foamed polyolefin-coated electric wire / cable and a foamed polyolefin-coated electric wire / cable.

In order to achieve the objective mentioned above, "the manufacturing method of foaming polyolefin covering electric wire and cable" concerning the present invention is characterized by following [1]-[3].
[1]
(1) A polyolefin is mixed with at least a base resin containing 20 to 95 parts by weight of a polyolefin resin and 5 to 80 parts by weight of a rubber component based on 100 parts by weight of a base resin, a crosslinking agent, a crosslinking aid, and a foaming agent Step (2) of Producing the Base Foamable Resin Composition The polyolefin foamable resin composition produced in the above step (1) is crosslinked, and the degree of crosslinking according to JIS C 3005 is 2 to 40%, JIS K Step (3) the step of obtaining a crosslinked product of a polyolefin-based foamable resin composition having a melt viscosity of 0.1 to 2.0 g / min measured at 190 ° C. under a load of 2.16 kgf in accordance with 7210 Step of extruding the cross-linked body obtained in 2) and forming a coating layer consisting of the cross-linked body on the outer periphery of the conductor (4) The covering layer formed in the step (3) has a foaming ratio of 3 to 30%. As foamy It is a manufacturing method of foaming polyolefin covering electric wire and cable including a process of making.
[2]
In the method for producing a foamed polyolefin-coated electric wire / cable according to the above [1],
The crosslinking agent is contained in an amount of 0.02 to 0.5 parts by weight with respect to 100 parts by weight of the base resin,
It is a manufacturing method of the foaming polyolefin covering electric wire and cable which contains the said crosslinking adjuvant 1 to 3 times quantity of the said crosslinking agent.
[3]
In the method for producing a foamed polyolefin-coated electric wire or cable according to the above [1] or [2],
The foaming agent is contained in an amount of 0.1 to 10 parts by weight with respect to 100 parts by weight of the base resin,
The polyolefin-based foamable resin composition further contains 10 to 90 parts by weight of a filler,
The method for producing a foamed polyolefin-coated electric wire or cable, which comprises 0.5 to 10 parts by weight of a lubricant.

  According to the method for producing a foamed polyolefin-coated electric wire or cable of the constitution of the above [1], the polyolefin foamable resin composition is crosslinked to have a specific degree of crosslinking before forming the coating layer on the outer periphery of the conductor. I am doing it. Furthermore, the composition of the base resin contained in the coating layer is a specific range. Therefore, the melt viscosity required at the time of extrusion is maintained in a specific range, the foaming is stabilized, the high foaming is realized, and the ease of tearing and the peelability are improved. In addition, sufficient mechanical properties such as high tensile strength and resistance to thermal deformation can also be obtained.

  Therefore, the method for producing the foamed polyolefin-coated electric wire / cable of the present configuration can achieve both excellent workability and mechanical properties.

  According to the method for producing a foamed polyolefin-coated electric wire / cable having the constitution of the above-mentioned [2], since the compounding amounts of the crosslinking agent and the crosslinking aid are specified, the polyolefin foamable resin composition after crosslinking is good. Provide good extrusion characteristics.

  Therefore, the excellent workability and mechanical properties of the wire / cable can be obtained, and the manufacturability is also improved.

  According to the method for producing a foamed polyolefin-coated electric wire / cable of the configuration of the above-mentioned [3], the content of the foaming agent, the content of the filler and the content of the lubricant are specified. The ease, peelability and mechanical properties can be further enhanced.

  Therefore, the workability and mechanical properties of the wire / cable can be further improved.

Furthermore, in order to achieve the above-mentioned object, the "foamed polyolefin-coated wire / cable" according to the present invention is characterized by the following [4].
[4]
A foamed polyolefin coated electric wire / cable having a conductor and a coating layer containing a base resin containing a foamed and crosslinked polyolefin resin on the outer periphery of the conductor,
The base resin contains 20 to 95 parts by weight of the polyolefin resin and 5 to 80 parts by weight of a rubber component with respect to 100 parts by weight of the base resin,
The foaming rate of the covering layer is 3 to 30%,
The degree of crosslinking according to JIS C 3005 of the coating layer is 2 to 40%, and the melt viscosity measured at 190 ° C. under a load of 2.16 kgf according to JIS K 7210 is 0.1 to 2.0 g / Characterized by being a minute,
Be a foamed polyolefin coated wire / cable.

  According to the foamed polyolefin-coated electric wire / cable of the configuration of the above-mentioned [4], the blending of the base resin contained in the coating layer, the foaming ratio of the coating layer, and the crosslinking degree and melt viscosity of the coating layer are specified. Stabilization, high foaming can be realized, and tearability and peelability are improved. In addition, mechanical properties such as sufficient tensile strength and thermal deformation can be obtained.

  Therefore, the foamed polyolefin-coated electric wire / cable of this configuration can achieve both excellent workability and mechanical properties.

  According to the present invention, a foamed polyolefin-coated electric wire which stabilizes foaming, realizes high foaming, improves tearability and peelability, has excellent workability and has sufficient mechanical properties. It is possible to provide a method for producing a cable and a foamed polyolefin-coated electric wire / cable produced by the method.

  The present invention has been briefly described above. Furthermore, the details of the present invention will be further clarified by reading the modes for carrying out the invention described below (hereinafter referred to as "embodiments") with reference to the attached drawings. .

FIG. 1 is a cross-sectional view of a foamed polyolefin-coated electric wire / cable according to the present embodiment, wherein (a) is a cross-sectional view of the foamed polyolefin-coated electric wire, and (b) is a cross-sectional view of the foamed polyolefin-coated cable. FIG. 2 is a cross-sectional view of another example of the foamed polyolefin-coated electric wire according to the present embodiment.

  Hereinafter, an embodiment of a method for producing a foamed polyolefin-coated electric wire / cable and a foamed polyolefin-coated electric wire / cable according to the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view of a foamed polyolefin-coated electric wire / cable according to the present embodiment, wherein (a) is a cross-sectional view of the foamed polyolefin-coated electric wire, and (b) is a cross-sectional view of the foamed polyolefin-coated cable.
As shown in FIG. 1A, the electric wire 1 in the present 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. Equipped with
Moreover, as shown in FIG.1 (b), the foaming polyolefin coated cable 10 which concerns on this embodiment is the some electric wire 1 (1a, 1b, 1c) bundled, and the periphery of the some electric wire 1 bundled. And a covering layer 4 as a covering layer.
FIG. 2 is a cross-sectional view of another example of the foamed polyolefin-coated electric wire according to the present embodiment. The electric wire 1 ′ in the present 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. And the upper layer 42.

  The conductor 2 may be only one strand or may be formed by bundling a plurality of strands. As a material of the conductor 2, for example, conductive metals such as copper, plated copper, copper alloy, aluminum, and aluminum alloy can be used.

  The insulator 3 can be provided as desired, and the material is not particularly limited, and can be appropriately selected from known insulators. For example, those comprising polyethylene, cross-linked polyethylene, and a vinyl mixture are preferably used Be

  As described above, the coating layer 4 is a polyolefin-based foamable resin composition, and the produced polyolefin-based foamable resin composition is crosslinked, and the degree of crosslinking according to JIS C 3005 is 2 to 40%. A crosslinked product of a polyolefin-based foamable resin composition having a melt viscosity of 0.1 to 2.0 g / min measured at 190 ° C. and a 2.16 kgf load according to JIS K 7210 was produced. It is formed by extruding a crosslinked body, forming a coating layer consisting of the crosslinked body on the outer periphery of the conductor 2 or on the outer periphery of the case where the insulator 3 is provided, and foaming it. This will be described below.

  The polyolefin-based foamable resin composition contains a base resin containing a polyolefin-based resin and a rubber component, a crosslinking agent, a crosslinking aid, and a foaming agent.

  The polyolefin resin is not particularly limited. For example, high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (L-LDPE), and ultra low density polyethylene Polyethylene (PE) such as (V-LDPE), polypropylene (PP), ethylene-propylene copolymer (EPR), ethylene-vinyl acetate copolymer (EVA), ethylene-methyl acrylate copolymer (EMA), and Ethylene-ethyl acrylate copolymer (EEA) etc. are mentioned. These polyolefin resins may be used alone or in combination of two or more.

  In the present invention, the melt viscosity (MFR) of a crosslinked product obtained by crosslinking a polyolefin-based foamable resin composition is 0.1 to 2.0 g / min. The melt viscosity (MFR) of the polyolefin resin contained in the polyolefin foamable resin composition before crosslinking is preferably 0.1 to 4.0 g / min in order to set the melt viscosity of the crosslinked product in the above range. It is more preferable that it is 0.4-2.5 g / min, and 0.4-1.0 g / min is more preferable. In the present invention, since the polyolefin-based foamable resin composition is crosslinked to have a specific degree of crosslinking before the formation of the coating layer on the outer periphery of the conductor, the melting temperature of the polyolefin-based resin is in the above range. As a result, it becomes possible to keep the melt viscosity required at the time of extrusion after crosslinking in the range of 0.1 to 2.0 g / min, and as a result, foaming is stabilized. The melt viscosity is a value measured at 190 ° C. under a load of 2.16 kgf in accordance with JIS K 7210: 2014.

Polyolefin resin is preferably a density of ^{0.85~1.00g / cm 3, 0.90~0.97g / cm} 3 is more preferable. The mechanical properties can be further improved by using a polyolefin resin having a density in the above range. The density is a value measured in accordance with JIS K 7112: 1999.

The blending amount of the polyolefin resin is 20 to 95 parts by weight based on 100 parts by weight of the whole base resin. Preferably it is 60 to 95 parts by weight, more preferably 70 to 95 parts by weight. When the content of the polyolefin resin is 20 parts by weight or more, the tensile strength is improved, and when the content is 95 parts by weight or less, the foaming is stabilized, and the easiness of tearing and the peelability are improved.
In addition, when using polypropylene (PP) as polyolefin resin, it is preferable that the compounding quantity is 30 weight part or less, when the whole base resin is 100 weight part. If it exceeds 30 parts by weight, the tearability and peelability may be reduced.

  The rubber component has a role of imparting rubber elasticity to the resin composition. Examples of the rubber component include ethylene / propylene / non-conjugated diene copolymer rubber (EPDM), styrene / ethylene / butylene / styrene copolymer (SEBS), styrene / butadiene / rubber (SBR), butadiene rubber (BR) And nitrile rubber (NBR) and the like.

  The compounding amount of the rubber component is 5 to 80 parts by weight based on 100 parts by weight of the whole base resin. The amount is preferably 5 to 40 parts by weight, more preferably 5 to 30 parts by weight. When the rubber component is 5 parts by weight or more, a decrease in melt viscosity after crosslinking can be suppressed, and when it is 80 parts by weight or less, a decrease in tensile strength can be suppressed.

Crosslinking agents include, but are not limited to, organic oxides. Specifically, as a crosslinking agent, dicumyl peroxide (DCP), 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 peroxide, 2,4-dichlorobenzoyl peroxide, tert-butylperoxybenzoate, tert-butylperoxy Isopropyl carbonate, diacetyl peroxide, lauroyl peroxide, Beauty tert- butyl cumyl peroxide, and the like. These can be used individually by 1 type or in combination of 2 or more types.
Among them, preferable crosslinking agents include 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane.

The crosslinking aid is not particularly limited, and examples thereof include compounds having two or more double bonds in the molecule, and specifically, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, Diacrylates such as 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 polyethylene glycol dimer Dimethacrylates such as acrylate; triacrylates such as trimethylolpropane triacrylate, tetramethylolmethane triacrylate, and pentaerythritol triacrylate; trimethacrylates such as trimethylolpropane trimethacrylate and trimethylolethane trimethacrylate; pentaerythritol tetraacrylate, And tetraacrylates such as tetramethylol methane tetraacrylate; divinyl aromatic compounds such as divinyl benzene; cyanuric acid such as triallyl cyanurate and triallyl isocyanurate; diallyl compounds such as diallyl phthalate; triallyl compounds and the like.
Among the preferable crosslinking assistants, triethylene glycol dimethacrylate is mentioned.

According to the present invention, by achieving quantitative balance between the crosslinking agent and the crosslinking assistant, good extrusion characteristics can be provided even after the polyolefin foamable resin composition is crosslinked.
That is, the blending amount of the crosslinking agent is preferably 0.02 to 0.5 parts by weight, and more preferably 0.02 to 0.1 parts by weight with respect to 100 parts by weight of the base resin. When the compounding amount of the crosslinking agent is 0.02 parts by weight or more, it is possible to provide good extrusion characteristics and improve the tensile strength, and by being 0.5 parts by weight or less, it is possible to provide good extrusion characteristics as well. The appearance after extrusion is also improved.
Moreover, 1 to 3 times amount of the said crosslinking agent is preferable, and, as for the compounding quantity of the said crosslinking adjuvant, 1.5 to 2.0 times amount is more preferable. When the compounding amount of the cross-linking coagent is at least 1 time the amount of the cross-linking agent, good extrusion characteristics can be provided and the appearance after extrusion is also improved. When the amount is 3 times or less, it is possible to provide good extrusion characteristics and to improve tensile strength.

As the foaming agent, known chemical decomposition type foaming agents or the like which generate carbon dioxide gas, nitrogen gas and the like by chemical decomposition can be used. For example, azo compounds such as azodicarbonamide (ADCA), N, N'- Nitroso compounds such as dinitrosopentamethylenetetramine, hydrazine derivatives such as 4,4′-oxybis (benzenesulfonylhydrazide) (OBSH) and hydrazodicarbonamide (HDCA), sodium hydrogencarbonate and the like can be mentioned.
The blending amount of the foaming agent is preferably 0.1 to 10 parts by weight, and more preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the base resin.

  In the covering layer 4, fillers, lubricants, antioxidants, processing aids, neutralizing agents, UV absorbers, pigments, antistatic agents, and dispersions, if necessary, as long as the effects of the present invention are not impaired. Various known additives such as agents can also be blended.

  Examples of fillers include organic bromine-containing flame retardants such as brominated ethylene bis phthalimide derivatives, bis brominated phenyl terephthalamide derivatives, brominated bisphenol derivatives, and 1,2-bis (bromophenyl) ethane; magnesium hydroxide And inorganic flame retardants such as aluminum hydroxide; phosphoric acid flame retardants such as aromatic condensed phosphate ester, ammonium polyphosphate and melamine phosphate; ammonium polyphosphate, melamine polyphosphate, piperazine polyphosphate, pyrophosphate Intomescent flame retardants such as ammonium, melamine pyrophosphate and piperazine pyrophosphate; light calcium carbonate, ground calcium carbonate, mica, pentonite, zeolite, slaked lime, kaolin, diatomaceous earth and the like.

  The lubricants include hydrocarbon lubricants, fatty acid lubricants, and ester lubricants.

  Examples of the antioxidant include phenol-based antioxidants, amine-based antioxidants, and phosphorus-based antioxidants.

  Examples of processing aids include petroleum oils such as paraffinic oils, aromatic oils, and naphthenic oils.

  As a ultraviolet absorber, a benzophenone series compound, a benzotriazole type compound, a salicylate type compound, a substituted tolyl type compound, a metal chelate type compound etc. are mentioned, for example.

  As the pigment, general inorganic pigments and organic pigments described in "Pigment Handbook (Edited by Japan Pigment Technology Association)" can be used. For example, as the inorganic pigment, (composite) metal oxides containing titanium such as titanium yellow, zinc oxide, iron oxide, zinc sulfide, antimony trioxide and the like can be mentioned. Examples of the organic pigment include pigments of phthalocyanine type, anthraquinone type, quinacridone type, azo type, isoindolinone type, quinophthalone type, perinone type, and perylene type.

  Examples of the antistatic agent include alkyl phosphoric acid esters and silicic acid compounds.

  Examples of the dispersant include acrylic dispersants, fatty acid ester dispersants, polyethylene glycol dispersants, nonionic surfactants, amphiphilic triphenylene derivatives, and pyrene derivatives.

  The polyolefin-based foamable resin composition in the present invention preferably contains a filler and a lubricant, and the amount thereof is preferably 10 to 90 parts by weight, based on 100 parts by weight of the base resin. 80 parts by weight is more preferable, and 30 to 60 parts by weight is further preferable. The lubricant is preferably 0.5 to 10 parts by weight, more preferably 1 to 2 parts by weight. When the blending amount of the filler is 10 parts by weight or more, the tearability and peelability is improved, and when it is 90 parts by weight or less, the deterioration of the tensile strength is prevented. Further, when the compounding amount of the lubricant is 0.5 parts by weight or more, the tearability and peelability are improved, and when it is 10 parts by weight or less, the deterioration of the tensile strength is prevented.

As described above, the method for producing a foamed polyolefin-coated electric wire or cable of the present invention is characterized by including the following steps (1) to (4).
(1) A polyolefin is mixed with at least a base resin containing 20 to 95 parts by weight of a polyolefin resin and 5 to 80 parts by weight of a rubber component based on 100 parts by weight of a base resin, a crosslinking agent, a crosslinking aid, and a foaming agent Step (2) of Producing the Base Foamable Resin Composition The polyolefin foamable resin composition produced in the above step (1) is crosslinked, and the degree of crosslinking according to JIS C 3005 is 2 to 40%, JIS K Step (3) the step of obtaining a crosslinked product of a polyolefin-based foamable resin composition having a melt viscosity of 0.1 to 2.0 g / min measured at 190 ° C. under a load of 2.16 kgf in accordance with 7210 Step of extruding the cross-linked body obtained in 2) and forming a coating layer consisting of the cross-linked body on the outer periphery of the conductor (4) The covering layer formed in the step (3) has a foaming ratio of 3 to 30%. As foamy Process

  In the step (1), as a method of producing the polyolefin-based foamable resin composition, the above-mentioned base resin, crosslinking agent, crosslinking aid, and foaming agent, and other various additives added as needed The method of mixing uniformly using a well-known mixing means is illustrated.

  As described above, the content of the polyolefin resin relative to 100 parts by weight of the base resin is 20 to 95 parts by weight, and the content of the rubber component is 5 to 80 parts by weight.

  The method for crosslinking the polyolefin-based foamable resin composition in the step (2) is not particularly limited, and any conventionally known method can be adopted.

The degree of crosslinking of the polyolefin-based foamable resin composition is 2 to 40%. If the degree of crosslinking is less than 2%, the heat resistance decreases, and if the degree of crosslinking exceeds 40%, the workability decreases.
The degree of crosslinking should conform to the test in paragraph 25 of JIS C 3005: 2014. Specifically, 5 g of a sample of the crosslinkable polyolefin-based foamable resin composition is prepared, the sample is put into 100 g of xylene as a solvent and immersed, and the temperature of the solvent is kept at 120 ° C. for 24 hours, Remove the sample from the solvent, place it in a vacuum desiccator, and dry it at a temperature of 100 ± 2 ° C. and a vacuum degree of 1.3 kPa (10 Torr) or less for 24 hours or more. After drying, the weight of the sample (weight after test) is measured to the unit of mg and is shown as a percentage compared to the initial weight of the sample (weight before test).

  The melt viscosity of the polyolefin-based foamable resin composition after crosslinking is 0.1 to 2.0 g / min. When the melt viscosity is 0.1 g / min or more, the foaming ratio can be improved, and when the melt viscosity is 2.0 g / min or less, since the resin can be sufficiently pressurized, the foaming is stabilized. The melt viscosity is preferably 0.1 to 1.8 g / min, more preferably 0.5 to 1.5 g / min. The melt viscosity is a value measured at 190 ° C. under a load of 2.16 kgf in accordance with JIS K 7210.

  In the step (3), the method for extruding the crosslinked product is not particularly limited. For example, the crosslinked product obtained in the step (2) is extruded using an extruder such as a known single screw extruder or twin screw extruder, The coating layer 4 made of the cross-linked body can be formed on the outer periphery of the conductor 2. In the extrusion step, the coating layer is foamed as the step (4) to produce the foamed polyolefin-coated electric wire / cable of the present invention.

  The foamed polyolefin-coated electric wire / cable of the present invention can be produced by the above-mentioned production method, and a coating containing a conductor 2 and a base resin containing a foamed and crosslinked polyolefin resin on the outer periphery of the conductor 2 The base resin contains 20 to 95 parts by weight of the polyolefin resin and 5 to 80 parts by weight of the rubber component with respect to 100 parts by weight of the base resin, and the foaming ratio of the covering layer 4 is 3 .About.30%, the degree of crosslinking according to JIS C 3005 of the covering layer 4 is 2 to 40%, and the melt viscosity according to JIS K 7210 is 0.1 to 2.0 g / min. I assume.

  According to the foamed polyolefin-coated electric wire / cable, the composition of the base resin contained in the coating layer, the foaming ratio of the coating layer, and the degree of crosslinking of the coating layer and the melt viscosity are specified, and the foaming is stabilized and the high foaming is achieved. It is realized and the tearability and peelability is improved. In addition, mechanical properties such as sufficient tensile strength and thermal deformation can be obtained.

  Here, when the foaming ratio of the covering layer 4 is 3% or more, the tearability and peelability is improved, and when it is 30% or less, mechanical properties such as tensile strength and heat deformation are improved. Do. The foam ratio is more preferably 5 to 25%. In the present invention, before the coating layer 4 is formed on the outer periphery of the conductor 2, the polyolefin-based foamable resin composition is crosslinked to stabilize the foam and increase the foam rate (for example, a foam rate of 10% or more) However, when the polyolefin foamable resin composition is crosslinked after forming the coating layer 4 on the outer periphery of the conductor 2, the foaming is not stabilized and the appearance becomes poor.

  The foaming ratio in the present invention is calculated from the ratio of specific gravity before and after foaming. Specifically, the specific gravity measurement value after foaming is divided by the specific gravity measurement value before foaming to calculate.

  Further, in the present invention, since the polyolefin-based foamable resin composition is crosslinked before forming the coating layer 4 on the outer periphery of the conductor 2, the radial orientation of the crosslinked product of the polyolefin-based resin in the coating layer 4 However, as compared with the axial orientation, this increases the ease of tearing and peeling in the longitudinal direction of the wire / cable. In addition, the orientation of the crosslinked product can be confirmed by SEM or the like in the advancing direction of the dispersed rubber component.

  As shown in FIG. 2, when the coating layer 4 is in the form of a two-layer structure of the lower layer 41 and the upper layer 42, for example, the density of the polyolefin resin in the lower layer 41 and the upper layer 42 is made different. Deformation characteristics, heat resistance, etc. can be shared by each layer.

  Hereinafter, the present invention will be further described by way of examples, but the present invention is not limited to the following examples.

The following materials were used.
EVA: Mitsubishi Chemical Corporation A543
EPDM: EP07AP manufactured by JSR Corporation
Crosslinking agent (organic peroxide): manufactured by NOF Corporation Perhexa 25B (2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane)
Crosslinking auxiliary agent: Shin Nakamura Chemical Industry Co., Ltd. NK ester 3G (triethylene glycol dimethacrylate)
Filler: Magnesium hydroxide Lubricant: Calcium oil stearate manufactured by NOF Corp. Foaming agent: manufactured by Nagawa Chemical Industries, Ltd. ADCA (azodicarbonamide) EV 405 D

[Test wire: Examples 1 to 34]
Each component was kneaded with a kneader at a temperature of 200 ° C. according to the compounding amount (parts by weight) shown in Table 1 to prepare a polyolefin-based foamable resin composition.
Subsequently, a crosslinking agent and a crosslinking aid were added, and the mixture was crosslinked by kneading at 190 ° C. for 3 minutes or more to prepare a crosslinked product.
Subsequently, using an extrusion molding machine, coat each crosslinked body with a 0.8 mm thick copper wire with a diameter of 0.8 mm, further covering with the crosslinked body with a thickness of 1.5 mm. The layers were formed to produce a test wire (flat type 3 × 2.0).

The following evaluation was performed about each test wire.
Melt viscosity (MFR): Measured at 190 ° C. under a 2.16 kgf load in accordance with JIS K 7210: 2014.
Degree of crosslinking: Measured in accordance with the test in paragraph 25 of JIS C 3005: 2014.
Foaming rate: Calculated by the ratio of specific gravity before and after foaming. Specifically, the specific gravity measurement value after foaming was divided by the specific gravity measurement value before foaming to calculate.
Foaming rate range: The foaming rate was measured at 10 points from a 1,000 m product. When the difference between the maximum value and the minimum value is less than ± 5%, it is described as A, and when the difference between the maximum value and the minimum value is less than ± 5%, it is described as B.
Tensile strength: Measured by carrying out the tensile test of Section 4.16 of JIS C 3005: 2014. A value of 10 MPa or more was taken as a standard value, one satisfying the standard value was described as A, and one not satisfying it was described as B.
Heating deformation (75 ° C.): Measured by carrying out the heating deformation in section 4.23 of JIS C 3005: 2014. Those satisfying the standard value were described as A, and those not satisfying the standard value were described as B.
Peelability: Insert a notch in the test cable, place a knife in the lower chuck in the tensile tester, and place a test cable with a notch in the upper chuck with the knife in place and conduct a tensile test Measured by The peel load of less than 40 N was described as A, and 40 N or more as B.
Extruded appearance: Butsu and the like were confirmed by visual inspection and palpation. No description was given as A, and Notsu was given as B.
The results are shown in Table 1.

[Test wire: Comparative examples 1 to 56]
Test wires were produced in the same manner as the above test wires: Examples 1 to 34 except that a polyolefin-based foamable resin composition was produced according to the compounding amounts (parts by weight) shown in Tables 2 to 5. The results are shown in Tables 2-5.

  Furthermore, based on various parameters of the foaming rate range, tensile strength, heat deformation (75 ° C.), peelability, and extrusion appearance measured and calculated in the test wires: Examples 1 to 34 and Comparative Examples 1 to 56, A comprehensive evaluation of various test wires was performed. In this comprehensive evaluation, the evaluation A represents that all the evaluations of the above-mentioned various parameters are A, the evaluation B represents that among the various parameters, there are four evaluations of A and one evaluation of B. The evaluation C represents that among the above-mentioned various parameters there are three evaluations of A and two evaluations of B, and the evaluation D is that there are two evaluations of A among the various parameters and three evaluations of B. The evaluation E represents that one of the above-mentioned various parameters is A and that of B is four, and the evaluation F represents that all the above-mentioned various parameters are B. .

  In the test electric wire of the example manufactured by carrying out the manufacturing method of the present invention, a polyolefin-based foamable resin composition specifying the composition and content of the base resin is used to form a coating layer on the outer periphery of the conductor In addition, since the crosslinking degree is made to be in the range of 2 to 40%, the melt viscosity required at the time of extrusion is kept in the range of 0.1 to 2.0 g / min, and the foaming is stabilized. The high foaming can be realized, and the tearability and the peelability are improved. In addition, mechanical properties such as high tensile strength and heat denaturation are obtained.

  On the other hand, in the test wire of the comparative example, in the polyolefin-based foamable resin composition used, any of the composition and content of the base resin, the degree of crosslinking, the melt viscosity, and the foaming rate is out of the scope of the present invention. The above performance was inferior to the test wire of the example.

  In addition, when the orientation direction of the crosslinked product of the coating layer in each test wire manufactured by carrying out the production method of the present invention was confirmed by the above method, the radial orientation of the crosslinked product was compared with the orientation in the axial direction. Was found to be large.

  The present invention is not limited to the above embodiments, and various modifications can be adopted within the scope of the present invention. For example, the present invention is not limited to the embodiments described above, and appropriate modifications, improvements, etc. are possible. In addition, the material, shape, size, number, arrangement location, and the like of each component in the embodiment described above are arbitrary and not limited as long as the present invention can be achieved.

Here, the features of the embodiment of the method for producing the foamed polyolefin coated electric wire / cable according to the present invention described above and the foamed polyolefin coated electric wire / cable produced by the producing method are briefly described in the following [1] to [4] respectively. I give up and list it.
[1]
The manufacturing method of the foaming polyolefin covering electric wire and cable including the process of following (1)-(4).
(1) A polyolefin is mixed with at least a base resin containing 20 to 95 parts by weight of a polyolefin resin and 5 to 80 parts by weight of a rubber component based on 100 parts by weight of a base resin, a crosslinking agent, a crosslinking aid, and a foaming agent Step (2) of Producing the Base Foamable Resin Composition The polyolefin foamable resin composition produced in the above step (1) is crosslinked, and the degree of crosslinking according to JIS C 3005 is 2 to 40%, JIS K Step (3) the step of obtaining a crosslinked product of a polyolefin-based foamable resin composition having a melt viscosity of 0.1 to 2.0 g / min measured at 190 ° C. under a load of 2.16 kgf in accordance with 7210 Step of extruding the cross-linked body obtained in 2) and forming a coating layer consisting of the cross-linked body on the outer periphery of the conductor (4) The covering layer formed in the step (3) has a foaming ratio of 3 to 30%. As foamy Process [2]
The polyolefin-based foamable resin composition is
The crosslinking agent is contained in an amount of 0.02 to 0.5 parts by weight with respect to 100 parts by weight of the base resin,
The crosslinking assistant is contained in an amount of 1 to 3 times the crosslinking agent,
The manufacturing method of the foamed polyolefin coated electric wire and cable as described in said (1).
[3]
In the polyolefin-based foamable resin composition,
The foaming agent is contained in an amount of 0.1 to 10 parts by weight with respect to 100 parts by weight of the base resin,
The polyolefin-based foamable resin composition further contains 10 to 90 parts by weight of a filler,
0.5 to 10 parts by weight of the lubricant is contained,
The manufacturing method of the foamed polyolefin coated electric wire and cable as described in said (1) or (2).
[4]
Foamed polyolefin-coated electric wire / cable (1, 10) comprising a conductor (2) and a coating layer (4) containing a base resin containing a foamed and crosslinked polyolefin resin on the outer periphery of the conductor (2) And
The base resin contains 20 to 95 parts by weight of the polyolefin resin and 5 to 80 parts by weight of a rubber component with respect to 100 parts by weight of the base resin,
The foaming ratio of the covering layer (4) is 3 to 30%,
The degree of crosslinking of the covering layer (4) according to JIS C 3005 is 2 to 40%, and the melt viscosity measured at 190 ° C. under a load of 2.16 kgf according to JIS K 7210 is 0.1 to 2 .0 g / min.,
Foamed polyolefin coated wire / cable (1, 10).

1 electric wire 2 conductor 3 insulator 4 covering layer 10 cable 41 lower layer 42 upper layer

Claims (4)

The manufacturing method of the foaming polyolefin covering electric wire and cable including the process of following (1)-(4).
(1) A polyolefin is mixed with at least a base resin containing 20 to 95 parts by weight of a polyolefin resin and 5 to 80 parts by weight of a rubber component based on 100 parts by weight of a base resin, a crosslinking agent, a crosslinking aid, and a foaming agent Step (2) of Producing the Base Foamable Resin Composition The polyolefin foamable resin composition produced in the above step (1) is crosslinked, and the degree of crosslinking according to JIS C 3005 is 2 to 40%, JIS K Step (3) the step of obtaining a crosslinked product of a polyolefin-based foamable resin composition having a melt viscosity of 0.1 to 2.0 g / min measured at 190 ° C. under a load of 2.16 kgf in accordance with 7210 Step of extruding the cross-linked body obtained in 2) and forming a coating layer consisting of the cross-linked body on the outer periphery of the conductor (4) The covering layer formed in the step (3) has a foaming ratio of 3 to 30%. As foamy Process The polyolefin-based foamable resin composition is
The crosslinking agent is contained in an amount of 0.02 to 0.5 parts by weight with respect to 100 parts by weight of the base resin,
The crosslinking assistant is contained in an amount of 1 to 3 times the crosslinking agent,
The manufacturing method of the foamed polyolefin coated electric wire and cable of Claim 1. In the polyolefin-based foamable resin composition,
The foaming agent is contained in an amount of 0.1 to 10 parts by weight with respect to 100 parts by weight of the base resin,
The polyolefin-based foamable resin composition further contains 10 to 90 parts by weight of a filler,
0.5 to 10 parts by weight of a lubricant,
The manufacturing method of the foamed polyolefin coated electric wire and cable of Claim 1 or 2. A foamed polyolefin coated electric wire / cable having a conductor and a coating layer containing a base resin containing a foamed and crosslinked polyolefin resin on the outer periphery of the conductor,
The base resin contains 20 to 95 parts by weight of the polyolefin resin and 5 to 80 parts by weight of a rubber component with respect to 100 parts by weight of the base resin,
The foaming rate of the covering layer is 3 to 30%,
The degree of crosslinking according to JIS C 3005 of the coating layer is 2 to 40%, and the melt viscosity measured at 190 ° C. under a load of 2.16 kgf according to JIS K 7210 is 0.1 to 2.0 g / Characterized by being a minute,
Foamed polyolefin coated wires and cables.

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