JP6962682B2 - 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 using non-halogen compositions that do not generate harmful halogen gas during incineration are becoming widespread. In addition, various proposals have been made for electric wires and cables using non-halogen compositions.

Polyolefin-based resins are examples of non-halogen compositions used for 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.

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 an unsaturated carboxylic acid or a derivative thereof and / or a styrene block copolymer containing 10 to 40% by mass of an 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.

Japanese Unexamined Patent Publication No. 2001-325833

However, in the above-mentioned conventional technology, 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 There is a problem that the ease of tearing and peeling of the wire deteriorates and the workability is inferior.

The present invention has been made in view of the above circumstances, and an object of the present invention is to improve the ease of tearing and peeling property, and to have excellent workability and sufficient mechanical properties. -To provide a method for manufacturing a 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 a step of mixing a base resin containing a polyolefin resin, a cross-linking agent, a cross-linking aid, and a foaming agent to prepare a polyolefin-based foamable resin composition (2) The polyolefin prepared in the step (1). Step of cross-linking the based foamable resin composition to obtain a crosslinked product of the polyolefin-based foamable resin composition (3) Extruding the cross-linked product obtained in the above step (2), and coating the outer periphery of the conductor with the cross-linked product. A step of forming a layer , and (4) a step of foaming the coating layer formed in the step (3).
Have,
When the entire base resin is 100 parts by weight, the polyolefin resin is contained in an amount of 60 to 95 parts by weight and the rubber component is contained in an amount of 5 to 40 parts by weight.
It must be a method for manufacturing foamed polyolefin-coated electric wires and cables.
[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.
The cross-linking aid is contained in an amount of 1 to 3 times that of the cross-linking agent.
It must be a method for manufacturing foamed polyolefin-coated electric wires and cables.
[3]
In the method for manufacturing a foamed polyolefin-coated electric wire / cable according to the above [2],
The base resin contains 60 to 95 parts by weight of the polyolefin resin and 5 to 40 parts by weight of a rubber component.
The content of the foaming agent is 0.1 to 10 parts by weight.
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,
It must be a method for manufacturing foamed polyolefin-coated electric wires and cables.

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 before forming a coating layer on the outer periphery of the conductor. Therefore, 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 producing a foamed polyolefin-coated electric wire / cable having the configuration of [3] above, the composition of the base resin in the polyolefin-based foamable resin composition, its content, the content of the foaming agent, the content of the filler, and the lubricant. Since the content of the resin is specified, it is possible to further improve the stabilization of foaming, the ease of tearing, the peelability, and the mechanical properties.

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 foamed base resin on the outer periphery of the conductor.
The foaming rate of the coating layer is 3 to 30%, and the coating layer has a foaming rate of 3 to 30%.
The orientation of the radial cross-linked product of the polyolefin resin in the coating layer is rather large as compared to the orientation in the axial direction,
When the entire base resin is 100 parts by weight, the polyolefin resin is contained in an amount of 60 to 95 parts by weight and the rubber component is contained in an amount of 5 to 40 parts by weight.
Must be a foamed polyolefin-coated wire / cable.

According to the foamed polyolefin-coated electric wire / cable having the configuration of [4] above, since the foaming rate of the coating layer and the orientation direction of the crosslinked product of the polyolefin resin are specified, the foaming is stabilized and high foaming is realized. , The ease of tearing and peeling are improved. 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 method for manufacturing a foamed polyolefin-coated electric wire / cable having improved tearability and peelability, excellent workability, and sufficient mechanical properties, and foaming manufactured by the manufacturing method. Polyolefin-coated electric wires and cables 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 a foamed polyolefin-coated electric wire / cable and an embodiment of 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 prepares a polyolefin-based foamable resin composition, cross-links the prepared polyolefin-based foamable resin composition, extrudes the obtained crosslinked product, and insulates the outer periphery of the conductor 2. When the body 3 is provided, a coating layer made of the crosslinked body is formed on the outer periphery thereof, and the body 3 is formed by foaming the coating layer. This will be described below.

The polyolefin-based foamable resin composition contains a base resin containing a polyolefin-based resin, 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.
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. Further, the polyolefin-based resin preferably has a melt viscosity (MFR) of 0.4 to 2.5, more preferably 0.4 to 1.0. When the melting temperature of the polyolefin resin is within the above range, the extrusion processability is improved.
The density referred to in the present invention is a value measured in accordance with JIS K7112, and MFR is a value measured in accordance with JIS K7210 at 190 ° C. and a 2.16 kgf load.

As the base resin, components other than the polyolefin-based resin can be appropriately used as needed as long as the effects of the present invention are not impaired. Examples of such a component include a rubber component, which includes ethylene / propylene / non-conjugated diene copolymer rubber (EPDM), styrene / ethylene / butylene / styrene copolymer (SEBS), and styrene / butadiene / rubber (SBR). ), Butadiene rubber (BR), nitrile rubber (NBR) and the like.
The amount of the rubber component to be blended is preferably 60 to 95 parts by weight for the polyolefin resin and 5 to 40 parts by weight for the rubber component when the entire base resin is 100 parts by weight. More preferably, the polyolefin-based resin is 70 to 95 parts by weight, and the rubber component is 5 to 40 parts by weight.
The rubber component has a role of imparting rubber elasticity to the resin composition.
When the amount of the polyolefin resin is 60 parts by weight or more, the tensile strength is improved, and when the amount is 95 parts by weight or less, the ease of tearing and the peelability are improved.
Further, when the rubber component is 5 parts by weight or more, the tearability and peelability are improved, and when it is 40 parts by weight or less, the tensile strength is 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.

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.
Among them, 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, the coating layer 4 is provided with various known additives such as a filler, a lubricant, an antioxidant, a processing aid, a neutralizing agent, an ultraviolet absorber, a pigment, an antistatic agent, and a dispersant, if necessary. It 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 phosphate, 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, antimony trioxide and the like. Examples of organic pigments include phthalocyanine-based, anthraquinone-based, quinacridone-based, azo-based, isoindolinone-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. ~ 60 parts by weight is more 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 90 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 a step of mixing a base resin containing a polyolefin resin, a cross-linking agent, a cross-linking aid, and a foaming agent to prepare a polyolefin-based foamable resin composition (2) The polyolefin prepared in the step (1). Step of cross-linking the based foamable resin composition to obtain a crosslinked product of the polyolefin-based foamable resin composition (3) Extruding the cross-linked product obtained in the above step (2), and coating the outer periphery of the conductor with the cross-linked product. Step of forming a layer (4) Step of foaming the coating layer formed in the above step (3)

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.

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.

From the viewpoint of the effect of the present invention, the degree of cross-linking of the polyolefin-based foamable resin composition is preferably 1 to 50%, more preferably 3 to 40%.
The degree of cross-linking shall be in accordance with the test of Section 27 of JIS C3005. 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).

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 manufactured by the above-mentioned manufacturing method, and has a conductor 2 and a coating layer 4 that is foamed and contains a polyolefin-based resin on the outer periphery of the conductor 2. The coating layer 4 has a foaming rate of 3 to 30%, and the radial orientation of the crosslinked product of the polyolefin-based resin in the coating layer 4 is larger than that in the axial direction.
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. 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.

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
PP: Novatec BC8A manufactured by Nippon Polypropylene Co., Ltd.
EPDM: EP07AP manufactured by JSR Corporation
Organic peroxide: NOF Corporation Perhexa 25B (2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane)
Crosslinking aid: NK ester 3G (triethylene glycol dimethacrylate) manufactured by Shin-Nakamura Chemical Co., Ltd.
Filling agent: Magnesium hydroxide Lubricating agent: Calcium stearate manufactured by NOF Corporation Effervescent agent: Eiwa Kasei ADCA (azodicarbonamide) EV405D

[Test wires A1 to A99]
Each component was kneaded with a kneader at a temperature of 200 ° C. according to the blending amounts (parts by weight) shown in Tables 1 to 4 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.
Foaming rate: Calculated based on the ratio of specific gravity before pre-foaming and after foaming.
Tensile strength: Measured by carrying out the tensile test of JIS C3005, Section 4.16. 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 of JIS C3005 according to paragraph 4.23. 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 the tensile test. 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 also shown in Tables 1 to 4.

[Test wires B1 to B146]
Test wires were prepared in the same manner as the above test wires A1 to A99, except that the polyolefin-based foamable resin composition was prepared according to the blending amounts (parts by weight) shown in Tables 5 to 10. The results are shown in Tables 5-10.

Furthermore, comprehensive evaluation of various test wires was performed based on various parameters of tensile strength, thermal deformation (75 ° C.), peelability, and extruded appearance measured and calculated for the test wires A1 to A99 and B1 to B146. .. 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 three and the evaluation of B is one among the various parameters. , Evaluation C indicates that there are two evaluations of A and two evaluations of B among the various parameters described above, and evaluation D is one evaluation of A and three evaluations of B among the various parameters described above. It means that there is, and the evaluation E means that all the evaluations among the above-mentioned various parameters are B.

Each test wire manufactured by carrying out the manufacturing method of the present invention achieves higher foaming than the test wire manufactured by a conventional method of cross-linking a polyolefin-based foamable resin composition after forming a coating layer. It was possible, and the ease of tearing and peeling were improved. In addition, mechanical properties such as high tensile strength and resistance to heat denaturation were also obtained.
In particular, the test wires A1 to A99 produced by the method for producing a foamed polyolefin-coated electric wire / cable having the configuration of the present invention have a composition of a base resin in a polyolefin-based foamable resin composition, its content, a foaming agent content, and filling. Since the content of the material and the content of the lubricant were specified, the overall evaluation was A, and it was possible to further improve the stabilization of foaming, the ease of tearing and peeling, and the mechanical properties. ..

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 and are not limited as long as the present invention can be achieved.

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 a step of mixing a base resin containing a polyolefin resin, a cross-linking agent, a cross-linking aid, and a foaming agent to prepare a polyolefin-based foamable resin composition (2) The polyolefin prepared in the step (1). Step of cross-linking the based foamable resin composition to obtain a crosslinked product of the polyolefin-based foamable resin composition (3) Extruding the cross-linked product obtained in the above step (2), and coating the outer periphery of the conductor with the cross-linked product. Step of forming a layer (4) Step of foaming the coating layer formed in the step (3) [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 base resin contains 60 to 95 parts by weight of the polyolefin resin and 5 to 40 parts by weight of a rubber component.
The content of the foaming agent is 0.1 to 10 parts by weight.
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 (2) above.
[4]
A foamed polyolefin-coated electric wire / cable (1,10) having a conductor (2) and a coating layer (4) that is foamed and contains a polyolefin-based resin on the outer periphery of the conductor (2).
The foaming rate of the coating layer (4) is 3 to 30%.
The coating layer (4) is characterized in that the orientation of the crosslinked product of the polyolefin resin in the radial direction is larger than that in the axial direction.
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 (2)

(1) At least a step of mixing a base resin containing a polyolefin resin, a foaming agent , a filler, and a lubricant to prepare a polyolefin-based foamable resin composition (2) A step of producing a polyolefin-based foaming resin composition in the above step (1). Step of adding a cross-linking agent and a cross-linking aid to the sex resin composition and then cross-linking to obtain a cross-linked product of a polyolefin-based foamable resin composition (3) Extruding the cross-linked product obtained in the above step (2) to conduct a conductor. It has a step of forming a coating layer made of the crosslinked body on the outer periphery of the crosslinked body, and (4) a step of foaming the coating layer formed in the step (3).
The polyolefin-based foamable resin composition is
When the entire base resin is 100 parts by weight, the polyolefin resin is contained in an amount of 60 to 95 parts by weight, and the rubber component is contained in an amount of 5 to 40 parts by weight.
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 filler is contained in an amount of 10 to 90 parts by weight based on 100 parts by weight of the base resin.
The lubricant is contained in an amount of 0.5 to 10 parts by weight based on 100 parts by weight of the base resin.
In the polyolefin-based foamable resin composition,
0.02 to 0.5 parts by weight of the cross-linking agent is added to 100 parts by weight of the base resin, and 1 to 3 times the amount of the cross-linking agent is added to 100 parts by weight of the base resin. do,
Manufacturing method of foamed polyolefin coated electric wire / cable. A foamed polyolefin-coated electric wire / cable having a conductor and a coating layer containing a foamed base resin on the outer periphery of the conductor.
The foaming rate of the coating layer is 3 to 30%, and the coating layer has a foaming rate of 3 to 30%.
The radial orientation of the crosslinked product of the polyolefin resin in the coating layer is larger than that in the axial direction.
The coating layer is
When the entire base resin is 100 parts by weight, the polyolefin resin is contained in an amount of 60 to 95 parts by weight, and the rubber component is contained in an amount of 5 to 40 parts by weight.
The filler is contained in an amount of 10 to 90 parts by weight based on 100 parts by weight of the base resin.
The lubricant is contained in an amount of 0.5 to 10 parts by weight based on 100 parts by weight of the base resin.
Foamed polyolefin coated electric wire / cable.

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