JP6940367B2 - Manufacturing method of foamed polyolefin-coated electric wire / cable and foamed polyolefin-coated electric wire / cable - Google Patents

Description

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

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

Polyolefin-based resins are examples of non-halogen compositions used for coating electric wires and cables. Therefore, in recent years, non-halogen flame-retardant resin compositions in which a metal hydroxide is blended with a polyolefin resin as a flame retardant have come to be widely used. Further, conventionally, for the purpose of improving tearability and peeling property, a technique of adding a foaming agent to a non-halogen flame-retardant resin composition and foaming it at the time of manufacturing an electric wire / cable has been known.

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

In Patent Document 2 below, a resin composition in which a mixture of a polyolefin resin and a polyphenylene ether is used as a base polymer and a non-halogen flame retardant such as magnesium hydroxide is added thereto is used, and a chemical foam extrusion method or gas foaming is used. A shielded electric wire in which an insulating layer is formed by foam extrusion by an extrusion method has been proposed.

Japanese Unexamined Patent Publication No. 2001-325833 Japanese Unexamined Patent Publication No. 2001-52537

However, in Patent Document 1, it is necessary to add 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 electric wire / cable is torn. There is a problem that the ease of peeling and peeling are deteriorated and the workability is inferior.

Further, in Patent Document 2, in order to improve heat resistance and chemical resistance, irradiation cross-linking of a foamed insulator is performed by a method such as irradiating ionizing radiation such as γ-rays, but in general, irradiation cross-linking is large. In addition to the need for the above equipment, there is a problem that the production speed is low and the production efficiency is low.
Further, as a method for cross-linking these resin compositions, silane cross-linking and the like are also known. However, since silane cross-linking is carried out when the resin composition is extruded and then submerged in a water tank or the like, it is cross-linked immediately 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 circumstances, and an object of the present invention is to have good 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 manufacturing a foamed polyolefin-coated electric wire / cable and a foamed polyolefin-coated electric wire / cable.

In order to achieve the above-mentioned object, the "method for manufacturing a foamed polyolefin-coated electric wire / cable" according to the present invention is characterized by the following [1] to [3].
[1]
(1) At least 100 parts by weight of the base resin is mixed with 20 to 95 parts by weight of the polyolefin resin and 5 to 80 parts by weight of the rubber component, and a cross-linking agent, a cross-linking aid, and a foaming agent are mixed to form a polyolefin. Steps for Producing the Foamable Resin Composition (2) The polyolefin-based foamable resin composition prepared in the step (1) is crosslinked, and the degree of cross-linking according to JIS C 3005 is 2 to 40%, and JIS K Step (3) The step (3) for obtaining a crosslinked body 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 7210. Step of extruding the crosslinked body obtained in 2) to form a coating layer made of the crosslinked body on the outer periphery of the conductor (4) The coating layer formed in the step (3) has a foaming rate of 3 to 30%. It is a method of manufacturing a foamed polyolefin-coated electric wire / cable including a step of foaming.
[2]
In the method for manufacturing a foamed polyolefin-coated electric wire / cable according to the above [1],
The cross-linking agent is contained in an amount of 0.02 to 0.5 parts by weight based on 100 parts by weight of the base resin.
A method for manufacturing a foamed polyolefin-coated electric wire / cable, which contains the cross-linking aid in an amount of 1 to 3 times that of the cross-linking agent.
[3]
In the method for manufacturing a foamed polyolefin-coated electric wire / cable according to the above [1] or [2].
The foaming agent is contained in an amount of 0.1 to 10 parts by weight based on 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.
A method for manufacturing a foamed polyolefin-coated electric wire / cable containing 0.5 to 10 parts by weight of a lubricant.

According to the method for manufacturing a foamed polyolefin-coated electric wire / cable having the above configuration [1], the polyolefin-based foamable resin composition is crosslinked so as to have a specific degree of cross-linking before forming a coating layer on the outer periphery of the conductor. I'm letting you. Further, the blending of the base resin contained in the coating layer is within a specific range. Therefore, the melt viscosity required at the time of extrusion is maintained in a specific range, foaming is stabilized, high foaming is realized, and easiness of tearing and peeling property are improved. In addition, sufficient mechanical properties such as high tensile strength and resistance to thermal deformation can be obtained.

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

According to the method for producing a foamed polyolefin-coated electric wire / cable having the configuration of [2] above, since the blending amounts of the cross-linking agent and the cross-linking aid are specified, it is better than the polyolefin-based foamable resin composition after cross-linking. Can provide good extrusion characteristics.

Therefore, excellent workability and mechanical properties of electric wires and cables can be obtained, and manufacturability is also improved.

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

Therefore, the workability and mechanical properties of electric wires and cables can be further improved.

Further, in order to achieve the above-mentioned object, the "foamed polyolefin-coated electric 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-based 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 coating layer is 3 to 30%, and the foaming rate is 3 to 30%.
The degree of cross-linking of the coating layer according to JIS C 3005 is 2 to 40%, and the melt viscosity measured at 190 ° C. and 2.16 kgf load according to JIS K 7210 is 0.1 to 2.0 g / g. Characterized by being minutes,
Being a foamed polyolefin-coated electric wire / cable.

According to the foamed polyolefin-coated electric wire / cable having the configuration of [4] above, the composition of the base resin contained in the coating layer, the foaming rate of the coating layer, the degree of cross-linking of the coating layer and the melt viscosity are specified, and foaming occurs. Stabilizes, achieves high foaming, and improves tearability and peelability. In addition, sufficient mechanical properties such as sufficient tensile strength and thermal deformation can be obtained.

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

According to the present invention, a foamed polyolefin-coated electric wire that stabilizes foaming, realizes high foaming, improves tearability and peelability, has excellent workability, and also has sufficient mechanical properties. A method for manufacturing a cable and a foamed polyolefin-coated electric wire / cable manufactured by the manufacturing method can be provided.

The present invention has been briefly described above. Further, the details of the present invention will be further clarified by reading through the embodiments described below (hereinafter referred to as "embodiments") with reference to the accompanying drawings. ..

1A and 1B are cross-sectional views of a foamed polyolefin-coated electric wire / cable according to the present embodiment, FIG. 1A is a cross-sectional view of a foamed polyolefin-coated electric wire, and FIG. 1B is a cross-sectional view of a 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 the foamed polyolefin-coated electric wire / cable manufacturing method and the foamed polyolefin-coated electric wire / cable according to the present invention will be described with reference to the drawings.

1A and 1B are cross-sectional views of a foamed polyolefin-coated electric wire / cable according to the present embodiment, FIG. 1A is a cross-sectional view of a foamed polyolefin-coated electric wire, and FIG. 1B is a cross-sectional view of a 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 that covers the outer periphery of the conductor 2, and a coating layer 4 that covers the outer periphery of the insulator 3. To be equipped.
Further, as shown in FIG. 1B, the foamed polyolefin-coated cable 10 according to the present embodiment has a plurality of bundled electric wires 1 (1a, 1b, 1c) and a peripheral edge of the bundled plurality of electric wires 1. It includes a coating layer 4 as a coating layer to cover.
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 that covers the outer periphery of the conductor 2, and a coating layer 4 that covers the outer periphery of the insulator 3, and the coating layer 4 is a lower layer 41. It has a two-layer structure consisting of an upper layer 42 and an upper layer 42.

The conductor 2 may be formed by bundling only one wire or by bundling a plurality of wires. As the material of the conductor 2, for example, a conductive metal 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 thereof is not particularly limited and can be appropriately selected from known insulators. For example, one made of polyethylene, cross-linked polyethylene, a vinyl mixture or the like is preferably used. Be done.

As described above, the coating layer 4 is prepared by preparing a polyolefin-based foamable resin composition, cross-linking the prepared polyolefin-based foamable resin composition, and having a degree of cross-linking according to JIS C 3005 of 2 to 40%. A crosslinked body 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 prepared and obtained. The crosslinked body is extruded to form a coating layer made of the crosslinked body on the outer periphery of the conductor 2 or, when the insulator 3 is provided, on the outer periphery thereof, and this is formed by foaming. 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 cross-linking agent, a cross-linking aid, and a foaming agent.

The polyolefin-based resin is not particularly limited, and is, 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-methylacrylate copolymer (EMA), and Examples thereof include polyethylene-ethyl acrylate copolymer (EEA). These polyolefin-based resins may be used alone or in combination of two or more.

The present invention is characterized in that the melt viscosity (MFR) of the crosslinked product obtained by cross-linking the polyolefin-based foamable resin composition is 0.1 to 2.0 g / min. In order to keep the melt viscosity of the crosslinked product in the above range, the melt viscosity (MFR) of the polyolefin-based resin contained in the polyolefin-based foamable resin composition before cross-linking is preferably 0.1 to 4.0 g / min. , 0.4 to 2.5 g / min, more preferably 0.4 to 1.0 g / min. In the present invention, the melting temperature of the polyolefin resin is within the above range in order to crosslink the polyolefin-based foamable resin composition so as to have a specific degree of crosslinking before forming the coating layer on the outer periphery of the conductor. As a result, the melt viscosity required for extrusion after crosslinking can be maintained 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. and a 2.16 kgf load 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. By using a polyolefin resin having a density in the above range, the mechanical properties can be further improved. The above density is a value measured according to JIS K 7112: 1999.

The blending amount of the polyolefin resin is 20 to 95 parts by weight when the entire base resin is 100 parts by weight. It is preferably 60 to 95 parts by weight, more preferably 70 to 95 parts by weight. When the amount of the polyolefin resin is 20 parts by weight or more, the tensile strength is improved, and when the amount is 95 parts by weight or less, the foaming is stabilized, and the ease of tearing and the peelability are improved.
When polypropylene (PP) is used as the polyolefin resin, the blending amount thereof is preferably 30 parts by weight or less when the entire base resin is 100 parts by weight. If it exceeds 30 parts by weight, the ease of tearing and the peelability may decrease.

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), and butadiene rubber (BR). , And nitrile rubber (NBR) and the like.

The blending amount of the rubber component is 5 to 80 parts by weight when the entire base resin is 100 parts by weight. It 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, the decrease in melt viscosity after crosslinking can be suppressed, and when it is 80 parts by weight or less, the decrease in tensile strength can be suppressed.

Examples of the cross-linking agent include, but are not limited to, organic oxides. Specifically, as the cross-linking 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) hexin-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 Examples thereof include isopropyl carbonate, diacetyl peroxide, lauroyl peroxide, tert-butyl cumyl peroxide and the like. These can be used alone or in combination of two or more.
Of these, preferred cross-linking agents include 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane.

The cross-linking aid is not particularly limited, and examples thereof include compounds having two or more double bonds in the molecule, specifically 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, and the like. Diacrylates such as neopentyl glycol diacrylate, diethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, trimethylolpropylene diacrylate, and polypropylene glycol diacrylate; 1,3-butanediol dimethacrylate, 1,6- Dimethacrylates such as hexanediol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, and polyethylene glycol dimethacrylate; trimethylolpropane triacrylate, tetramethylolmethanetriacrylate, and pentaerythritol triacrylate. Aacrylates; trimethacrylates such as trimethylolpropane trimethacrylate and trimethylolethanetrimethacrylate; tetraacrylates such as pentaerythritol tetraacrylate and tetramethylolmethane tetraacrylate; divinyl aromatic compounds such as divinylbenzene; triallyl cyanurate, and Cyanurates such as triallyl isocyanurate; diallyl compounds such as diallyl phthalate; triaryl compounds and the like can be mentioned.
Among them, a preferable cross-linking aid is triethylene glycol dimethacrylate.

According to the present invention, by achieving a quantitative balance between the cross-linking agent and the cross-linking aid, it is possible to provide good extrusion characteristics even after the polyolefin-based foamable resin composition has been cross-linked.
That is, the blending amount of the cross-linking agent is preferably 0.02 to 0.5 parts by weight, more preferably 0.02 to 0.1 parts by weight, based on 100 parts by weight of the base resin. When the blending amount of the cross-linking agent is 0.02 parts by weight or more, good extrusion characteristics can be provided and the tensile strength is improved, and when it is 0.5 parts by weight or less, good extrusion characteristics can be provided. The appearance after extrusion is also improved.
The amount of the cross-linking aid compounded is preferably 1 to 3 times, more preferably 1.5 to 2.0 times the amount of the cross-linking agent. When the blending amount of the cross-linking aid is 1 times or more 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, good extrusion characteristics can be provided and the tensile strength is improved.

As the foaming agent, a known chemically decomposed foaming agent or the like that generates carbon dioxide gas, nitrogen gas or the like by chemical decomposition can be used. For example, an azo compound such as azodicarbonamide (ADCA), N, N'- Examples thereof include nitroso compounds such as dinitrosopentamethylenetetramine, hydrazine derivatives such as 4,4'-oxybis (benzenesulfonylhydrazide) (OBSH) and hydrazodicarbonamide (HDCA), and sodium hydrogencarbonate.
The blending amount of the foaming agent is preferably 0.1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the base resin.

Further, in the coating layer 4, as long as the effect of the present invention is not impaired, a filler, a lubricant, an antioxidant, a processing aid, a neutralizing agent, an ultraviolet absorber, a pigment, an antistatic agent, and a dispersion are provided. Various known additives such as agents can also be blended.

Examples of the filler include organic bromine-containing flame retardants such as brominated ethylene bisphthalimide derivative, bisbrominated phenylterephthalamide derivative, brominated bisphenol derivative, and 1,2-bis (bromophenyl) ethane; magnesium hydroxide. , And inorganic flame retardants such as aluminum hydroxide; phosphoric acid flame retardants such as aromatic condensed phosphoric acid 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, heavy calcium carbonate, mica, pentonite, zeolite, delime, kaolin, and sucrose soil.

Examples of the lubricant include hydrocarbon-based lubricants, fatty acid-based lubricants, ester-based lubricants and the like.

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

Examples of the processing aid include petroleum-based oils such as paraffin-based oils, aromatic-based oils, and naphthenic-based oils.

Examples of the ultraviolet absorber include benzophenone compounds, benzotriazole compounds, salicylate compounds, substituted trill compounds, metal chelate compounds and the like.

As the pigment, general inorganic pigments and organic pigments described in "Pigment Handbook (edited by Japan Pigment Technology Association)" can be used. For example, examples of the inorganic pigment include (composite) metal oxides containing titanium 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, isoindoleinone-based, quinophthalone-based, perinone-based, and perylene-based pigments.

Examples of the antistatic agent include an alkyl phosphate ester and a silicic acid compound.

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

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, 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 peeling property are improved, and when it is 90 parts by weight or less, deterioration of the tensile strength is prevented. Further, when the blending amount of the lubricant is 0.5 parts by weight or more, the tearability and peeling property are improved, and when it is 10 parts by weight or less, deterioration of the tensile strength is prevented.

The method for manufacturing a foamed polyolefin-coated electric wire / cable of the present invention is characterized by including the following steps (1) to (4) as described above.
(1) At least 100 parts by weight of the base resin is mixed with 20 to 95 parts by weight of the polyolefin resin and 5 to 80 parts by weight of the rubber component, and a cross-linking agent, a cross-linking aid, and a foaming agent are mixed to form a polyolefin. Steps for Producing the Foamable Resin Composition (2) The polyolefin-based foamable resin composition prepared in the step (1) is crosslinked, and the degree of cross-linking according to JIS C 3005 is 2 to 40%, and JIS K Step (3) The step (3) for obtaining a crosslinked body 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 7210. Step of extruding the crosslinked body obtained in 2) to form a coating layer made of the crosslinked body on the outer periphery of the conductor (4) The coating layer formed in the step (3) has a foaming rate of 3 to 30%. The process of foaming

In the step (1), as a method for producing the polyolefin-based foamable resin composition, the above-mentioned base resin, cross-linking agent, cross-linking aid, and foaming agent, and various other additives added as needed are used. An example is a method of uniformly mixing using a known mixing means.

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

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

The degree of cross-linking of the polyolefin-based foamable resin composition is 2 to 40%. If the degree of cross-linking is less than 2%, the heat resistance is lowered, and if the degree of cross-linking exceeds 40%, the workability is lowered.
The degree of cross-linking shall be in accordance with the test of Section 25 of JIS C 3005: 2014. Specifically, 5 g of a sample of the crosslinked polyolefin-based foamable resin composition is prepared, the sample is immersed in 100 g of xylene as a solvent, the temperature of the solvent is maintained at 120 ° C. for 24 hours, and then , The sample is taken out from the solvent, placed in a vacuum desiccator, and dried 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 (mass after the test) is measured to the unit of mg and shown as a percentage compared to the initial weight of the sample (mass before the 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 rate can be improved, and when it is 2.0 g / min or less, sufficient pressure can be applied to the resin, so that foaming is stable. 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. and a 2.16 kgf load according to JIS K 7210.

In the step (3), the method for extruding the crosslinked product is not particularly limited, and for example, the crosslinked product obtained in the step (2) is extruded by a known extruder such as a single-screw extruder or a twin-screw extruder. A coating layer 4 made of the crosslinked body can be formed on the outer periphery of the conductor 2. Further, during this extrusion step, the coating layer is foamed as the step (4), and the foamed polyolefin-coated electric wire / cable of the present invention is manufactured.

The foamed polyolefin-coated electric wire / cable of the present invention can be produced by the above-mentioned manufacturing method, and is coated with a conductor 2 and a base resin containing a foamed and crosslinked polyolefin-based resin on the outer periphery of the conductor 2. It has a layer 4, 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, and the foaming ratio of the coating layer 4 is 3. It is characterized in that the degree of cross-linking of the coating layer 4 according to JIS C 3005 is 2 to 40%, and the melt viscosity according to JIS K 7210 is 0.1 to 2.0 g / min. And.

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

Here, when the foaming rate of the coating layer 4 is 3% or more, the ease of tearing and peeling property are improved, and when it is 30% or less, mechanical properties such as tensile strength and heat-resistant deformation are improved. do. The foaming rate is more preferably 5 to 25%. In the present invention, the polyolefin-based foamable resin composition is crosslinked before the coating layer 4 is formed on the outer periphery of the conductor 2, the foaming is stabilized, and the foaming is high (for example, a foaming rate of 10% or more). However, if the polyolefin-based foamable resin composition is crosslinked after the coating layer 4 is formed on the outer periphery of the conductor 2, the foaming is not stable and the appearance is poor.

The foaming rate referred to in the present invention is calculated from the specific gravity ratios before and after foaming. Specifically, it is calculated by dividing the measured value of specific gravity after foaming by the measured value of specific gravity before foaming.

Further, in the present invention, since the polyolefin-based foamable resin composition is crosslinked before the coating layer 4 is formed on the outer periphery of the conductor 2, the radial orientation of the crosslinked polyolefin-based resin in the coating layer 4 However, it becomes larger than the orientation in the axial direction, which improves the ease of tearing and the peelability in the longitudinal direction of the electric wire / cable. As for the orientation of the crosslinked product, the traveling direction of the dispersed rubber component can be confirmed by SEM or the like.

As shown in FIG. 2, when the coating layer 4 has a two-layer structure of the lower layer 41 and the upper layer 42, for example, the densities of the polyolefin-based resin in the lower layer 41 and the upper layer 42 are made different, and desired properties (for example, heating) are allowed. Deformation characteristics, heat resistance, etc.) can be shared by each layer.

Hereinafter, the present invention will be further described with reference to 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): Perhexa 25B (2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane) manufactured by NOF CORPORATION
Crosslinking aid: NK ester 3G (triethylene glycol dimethacrylate) manufactured by Shin Nakamura Chemical Industry Co., Ltd.
Filling agent: Magnesium hydroxide Lubricating agent: Calcium stearate manufactured by NOF Corporation Foaming agent: ADCA (azodicarbonamide) EV405D manufactured by Eiwa Kasei Kogyo Co., Ltd.

[Test wire: Examples 1 to 34]
Each component was kneaded with a kneader at a temperature of 200 ° C. according to the blending amount (part by weight) shown in Table 1 to prepare a polyolefin-based foamable resin composition.
Subsequently, a cross-linking agent and a cross-linking aid were added, and the cross-linking was carried out by kneading at 190 ° C. for 3 minutes or more to prepare a cross-linked product.
Subsequently, using an extrusion molding machine, each crosslinked body is coated with an insulator on a copper wire having a diameter of 2.0 mm so as to have a thickness of 0.8 mm, and further coated on the crosslinked body with the crosslinked body so as to have a thickness of 1.5 mm. A layer was formed to prepare a test electric wire (flat type 3 × 2.0).

The following evaluations were made for each test wire.
Melt viscosity (MFR): Measured according to JIS K 7210: 2014 at 190 ° C. and 2.16 kgf load.
Crosslinkability: Measured according to the test of Section 25 of JIS C 3005: 2014.
Foaming rate: Calculated based on the specific gravity ratio before and after foaming. Specifically, it was calculated by dividing the measured value of specific gravity after foaming by the measured value of specific gravity before foaming.
Foaming rate range: The foaming rate was measured at 10 points from the 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 performing the tensile test of Section 4.16 of JIS C 3005: 2014. 10 MPa or more was defined as a standard value, those satisfying the standard value were described as A, and those not satisfying the standard value were described as B.
Thermal deformation (75 ° C.): Measured by carrying out the thermal deformation according to Section 4.23 of JIS C 3005: 2014. Those satisfying the standard value are described as A, and those not satisfying the standard value are described as B.
Peelability: Make a notch in the test cable, install a knife in the lower chuck part of the tensile tester, and install the test cable with a notch in the upper chuck part with the knife bitten to perform a tensile test. It was measured by. A peeling load of less than 40 N was described as A, and a peeling load of 40 N or more was described as B.
Extruded appearance: The lumps were confirmed visually and by palpation. The absence of lumps was described as A, and the presence of lumps was described as B.
The results are shown in Table 1.

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

Further, the test electric wire: based on various parameters of foaming ratio range, tensile strength, heat deformation (75 ° C.), peelability, and extruded appearance measured and calculated in Examples 1 to 34 and Comparative Examples 1 to 56, Comprehensive evaluation of various test wires was performed. In this comprehensive evaluation, the evaluation A indicates that all the evaluations of the various parameters are A, and the evaluation B indicates that the evaluations of A are four and the evaluation of B is one among the various parameters. , Evaluation C means that A has 3 evaluations and B has 2 evaluations among the various parameters, and evaluation D has 2 evaluations of A and 3 evaluations of B among the various parameters. Evaluation E indicates that there is one evaluation of A and four evaluations of B among the various parameters, and evaluation F indicates that all evaluations of the various parameters are B. ..

In the test electric wire of the example produced by carrying out the production method of the present invention, a polyolefin-based foamable resin composition in which the composition of the base resin and its content are specified is used to form a coating layer on the outer periphery of the conductor. Since the cross-linking is performed so that the degree of cross-linking is within the range of 2 to 40%, the melt viscosity required for extrusion is maintained in the range of 0.1 to 2.0 g / min, and foaming is stable. , High foaming can be realized, and the ease of tearing and peeling are improved. In addition, mechanical properties such as high tensile strength and resistance to heat denaturation were also obtained.

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

When the orientation direction of the crosslinked product of the coating layer in each test wire manufactured by carrying out the manufacturing method of the present invention was confirmed by the above method, the orientation of the crosslinked product in the radial direction was compared with the orientation in the axial direction. Turned out to be big.

The present invention is not limited to each of 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 above-described embodiment, and can be appropriately modified, improved, and the like. In addition, the material, shape, dimensions, number, arrangement location, etc. of each component in the above-described embodiment are arbitrary as long as the present invention can be achieved, and are not limited.

Here, the features of the method for manufacturing the foamed polyolefin-coated electric wire / cable according to the present invention and the embodiment of the foamed polyolefin-coated wire / cable manufactured by the manufacturing method are briefly described below in [1] to [4], respectively. List them all together.
[1]
A method for manufacturing a foamed polyolefin-coated electric wire / cable, which comprises the following steps (1) to (4).
(1) At least 100 parts by weight of the base resin is mixed with 20 to 95 parts by weight of the polyolefin resin and 5 to 80 parts by weight of the rubber component, and a cross-linking agent, a cross-linking aid, and a foaming agent are mixed to form a polyolefin. Steps for Producing the Foamable Resin Composition (2) The polyolefin-based foamable resin composition prepared in the step (1) is crosslinked, and the degree of cross-linking according to JIS C 3005 is 2 to 40%, and JIS K Step (3) The step (3) for obtaining a crosslinked body 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 7210. Step of extruding the crosslinked body obtained in 2) to form a coating layer made of the crosslinked body on the outer periphery of the conductor (4) The coating layer formed in the step (3) has a foaming rate of 3 to 30%. Step of foaming [2]
The polyolefin-based foamable resin composition is
The cross-linking agent is contained in an amount of 0.02 to 0.5 parts by weight based on 100 parts by weight of the base resin.
The cross-linking aid is contained in an amount of 1 to 3 times that of the cross-linking agent.
The method for manufacturing a foamed polyolefin-coated electric wire / cable according to (1) above.
[3]
In the polyolefin-based foamable resin composition,
The foaming agent is contained in an amount of 0.1 to 10 parts by weight based on 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.
Contains 0.5 to 10 parts by weight of the lubricant.
The method for manufacturing a foamed polyolefin-coated electric wire / cable according to (1) or (2) above.
[4]
Foamed polyolefin-coated electric wires / cables (1,10) having 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 rate of the coating layer (4) is 3 to 30%.
The coating layer (4) has a degree of cross-linking of 2 to 40% according to JIS C 3005, and has a melt viscosity of 0.1 to 2 measured at 190 ° C. and a 2.16 kgf load according to JIS K 7210. It is characterized by being 0.0 g / min,
Foamed polyolefin coated electric wire / cable (1,10).

1 Electric wire 2 Conductor 3 Insulator 4 Coating layer 10 Cable 41 Lower layer 42 Upper layer

Claims (3)

A method for manufacturing a foamed polyolefin-coated electric wire / cable, which comprises the following steps (1) to (4).
(1) At least 100 parts by weight of the base resin is mixed with 20 to 95 parts by weight of the polyolefin resin and 5 to 80 parts by weight of the rubber component, and a cross-linking agent, a cross-linking aid, and a foaming agent are mixed to form a polyolefin. Steps for Producing the Foamable Resin Composition (2) The polyolefin-based foamable resin composition prepared in the step (1) is crosslinked, and the degree of cross-linking according to JIS C 3005 is 2 to 40%, and JIS K Step (3) The step (3) for obtaining a crosslinked body 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 7210. Step of extruding the crosslinked body obtained in 2) to form a coating layer made of the crosslinked body on the outer periphery of the conductor (4) The coating layer formed in the step (3) has a foaming rate of 3 to 30%. The process of foaming The polyolefin-based foamable resin composition is
The cross-linking agent is contained in an amount of 0.02 to 0.5 parts by weight based on 100 parts by weight of the base resin.
The cross-linking aid is contained in an amount of 1 to 3 times that of the cross-linking agent.
The method for manufacturing a foamed polyolefin-coated electric wire / cable according to 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 based on 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.
Contains 0.5 to 10 parts by weight of lubricant,
The method for manufacturing a foamed polyolefin-coated electric wire / cable according to claim 1 or 2.

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