JP7267859B2 - wire or cable - Google Patents

Description

The present invention relates to wires or cables.

Patent Document 1 describes a foamed resin composition in which a base resin made of polyolefin is mixed with a foaming agent and foamed. A foamed resin composition to which 0.01 to 0.5 parts by mass of magnesium oxide is added is described. Further, Patent Document 1 describes an electric wire/cable using the foamed resin composition as an insulator.

JP 2010-280838 A

However, in the electric wire/cable of Patent Document 1, there is a problem that the metal (conductor) is discolored.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electric wire or cable in which discoloration of metal (conductor) is suppressed.

In order to achieve the above object, an electric wire or cable according to the present invention is an electric wire or cable having a conductor and an insulating layer provided on the outer periphery of the conductor, wherein the insulating layer comprises polyolefin and a chemical foaming agent. wherein the chemical blowing agent is a composite blowing agent (A) containing azodicarbonamide and sodium hydrogen carbonate, or azodicarbonamide and 4,4′- A composite foaming agent (B) containing oxybis(benzenesulfonylhydrazide), wherein the chemical foaming agent is used in an amount of 0.1 parts by mass or more and 2.0 parts by mass or less with respect to 100 parts by mass of the polyolefin, The compounding ratio of azodicarbonamide to sodium hydrogen carbonate in the composite foaming agent (A) is 1/9 or more and 9/1 or less in mass ratio, and the composite foaming agent (B) is 4,4' -The blending ratio of azodicarbonamide to oxybis(benzenesulfonylhydrazide) is 1/9 or more and 9/1 or less in mass ratio, and the insulating layer has an expansion rate of 5% or more and 30% or less.

ADVANTAGE OF THE INVENTION The electric wire or cable which concerns on this invention is effective in the discoloration of a metal (conductor) being suppressed.

FIG. 1 is a cross-sectional view of a cable according to an embodiment. FIG. 2 is a cross-sectional view of another example of a cable according to an embodiment; FIG. 3 is a cross-sectional view of an electric wire (insulated electric wire) according to the embodiment.

EMBODIMENT OF THE INVENTION Below, embodiment which concerns on this invention is described in detail based on drawing. In addition, this invention is not limited by this embodiment. In addition, components in the following embodiments include components that can be easily replaced by those skilled in the art, or components that are substantially the same.

[Embodiment]
<Cable>
FIG. 1 is a cross-sectional view of a cable according to an embodiment. As shown in FIG. 1 , the cable 10 has a conductor 11 , an insulating layer 12 provided around the conductor 11 , and a sheath 13 provided around the insulating layer 12 .

The conductor 11 is composed of, for example, a single metal wire or a twisted wire in which a plurality of metal wires are twisted together. The stranded wire may be compressed. Examples of materials for the metal wire or metal wire include annealed copper, tinned annealed copper, copper alloys, aluminum, and aluminum alloys. If the conductor 11 is a single wire, the diameter is not particularly limited, but is, for example, 0.5 mm or ^more and 10.0 mm ^or less. is.

The insulation layer 12 is a foamed crosslinked polyolefin insulation layer containing silane crosslinked polyolefin obtained by silane crosslinking and foaming a foamable resin composition containing silane-grafted polyolefin and a chemical foaming agent. Although the thickness of the insulating layer 12 is not particularly limited, it is, for example, 1.0 mm or more and 3.0 mm or less. Crosslinked polyolefin materials, which have excellent electrical and heat resistance properties, are commonly used for the insulation layers of cables. As the crosslinked polyolefin material, polyethylene having a high melting point is generally selected in order to maintain heat resistance (heat deformation test). However, as a trade-off, there is a drawback that the material cost is high. Since the insulation layer of the cable according to the embodiment is the foamed crosslinked polyolefin insulation layer, the cable maintains heat resistance and has the advantage of being inexpensive to manufacture.

The silane-grafted polyolefin contained in the foamable resin composition is obtained, for example, by kneading a polyolefin, a silane coupling agent, and a radical generator. Specifically, this kneading results in a precursor composition comprising a silane-grafted polyolefin.

Polyolefins (olefin resins) include polyethylene, polypropylene, ethylene-ethyl acrylate copolymers, ethylene-methyl acrylate copolymers, and ethylene-vinyl acetate copolymers. These may be used individually by 1 type, or may use 2 or more types together. Polyethylene is preferably used as the polyolefin. Since polyethylene has a high melting point, it has excellent heat resistance when crosslinked.

Specific examples of polyethylene include high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (L-LDPE), and very low density polyethylene (V-LDPE). are mentioned.

Silane coupling agents are grafted onto polyolefins to provide cross-linking points between polyolefin molecular chains. Silane coupling agents include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane, allyltrimethoxysilane, and allyltriethoxysilane. These may be used individually by 1 type, or may use 2 or more types together.

A radical generator (crosslinker) acts as an initiator for the silane grafting reaction. Radical generators include dicumyl peroxide, α,α'-bis(t-butylperoxydiisopropyl)benzene, di-t-butyl peroxide, t-butylcumyl peroxide, di-benzoyl peroxide, 2, Organic peroxides such as 5-dimethyl-2,5-bis(t-butylperoxy)hexane, t-butylperoxypivalate and t-butylperoxy-2-ethylhexanoate can be mentioned. These may be used individually by 1 type, or may use 2 or more types together.

During the kneading, it is preferable to knead the cross-linking catalyst together. Examples of cross-linking catalysts include carboxylic acid salts such as dibutyltin monophthalate, dibutyltin diphthalate, dibutyltin monolaurate, dibutyltin dilaurate, dibutyltin monomaleate, dibutyltin dimaleate, tin octylate and dibutyltin oxide. These may be used individually by 1 type, or may use 2 or more types together.

During the kneading, the silane coupling agent is preferably used in an amount of 0.5 parts by mass or more and 2.0 parts by mass or less with respect to 100 parts by mass of the polyolefin. Moreover, it is preferable to use the radical generator in an amount of 0.05 parts by mass or more and 0.5 parts by mass or less with respect to 100 parts by mass of the polyolefin. Moreover, it is preferable to use the cross-linking catalyst in an amount of 0.05 parts by mass or more and 0.5 parts by mass or less with respect to 100 parts by mass of the polyolefin.

The kneading conditions are not particularly limited as long as a silane-grafted polyolefin can be obtained. For example, the above-mentioned kneading can be performed by blending the above-mentioned components in the above-mentioned amounts and using a mixer such as a Henschel mixer, a V-blender, a ribbon blender, or a tumbler mixer. This gives a silane-grafted polyolefin. Specifically, a precursor composition comprising a silane-grafted polyolefin is obtained.

The chemical blowing agent contained in the foamable resin composition is a composite blowing agent (A) containing azodicarbonamide (ADCA) and sodium bicarbonate, or azodicarbonamide (ADCA) and 4,4'-oxybis A composite foaming agent (B) containing (benzenesulfonyl hydrazide) (OBSH). Thus, the cable according to the embodiment uses sodium bicarbonate or OBSH together with ADCA. In the cable according to the embodiment, discoloration of the metal (conductor) is suppressed by using the chemical foaming agent.

By the way, the chemical foaming agent foams the foamable resin composition by being vaporized by thermal decomposition. ADCA generates NH ₃ gas as a thermal decomposition product, and biurea, cyanuric acid, and urazole remain as decomposition residues. ADCA decomposition gases and decomposition residues are known to have the potential to discolor metals. Patent Document 1 describes that the growth of generated decomposition residues can be suppressed by making ADCA fine particles and adding magnesium oxide. However, this does not mean that the decomposition residue is eliminated, and it is thought that there is a problem of metal discoloration due to adhesion.

On the other hand, the decomposition gases of sodium bicarbonate used in the cable according to the embodiment are CO ₂ and H ₂ O, and the decomposition residue is sodium carbonate. The decomposition gas of OBSH used in the cable according to the embodiment is N ₂ and H ₂ O, and the decomposition residue is p,p'-oxybis(benzenesulfinic acid). They do not tarnish metals (conductors).

By using sodium bicarbonate or OBSH together with ADCA, the decomposition gas and decomposition residue of ADCA that affect discoloration can be neutralized, so discoloration of the metal (conductor) can be suppressed.

In addition, sodium bicarbonate and OBSH have lower decomposition temperatures, so their use with ADCA allows for lower temperature extrusion than ADCA alone. Therefore, compared to using ADCA alone, premature crosslinking (scorch) is less likely to occur, and productivity is excellent.

The foamable resin composition contains 0.00 of a chemical foaming agent (composite foaming agent (A) or complex foaming agent (B)) per 100 parts by mass of the polyolefin before the silane grafting. It is contained in an amount of 1 part by mass or more and 2.0 parts by mass or less. If the amount is less than 0.1 parts by mass, the foaming rate may become too small, which is not preferable from the viewpoint of cost. On the other hand, if the amount is more than 2.0 parts by mass, the foaming ratio becomes too large, which may be undesirable from the viewpoint of heat resistance and tensile strength.

In the composite foaming agent (A), the blending ratio of azodicarbonamide to sodium hydrogencarbonate is 1/9 or more and 9/1 or less in mass ratio. In the composite foaming agent (B), the mass ratio of azodicarbonamide to 4,4'-oxybis(benzenesulfonylhydrazide) is 1/9 or more and 9/1 or less. When the blending ratio is 9/1 or less, discoloration of the metal (conductor) can be suitably suppressed. If the blending ratio is much smaller than 1/9, the foam cell diameter becomes too large, and there is a concern that the properties (mechanical and electrical) of the foam may deteriorate.

The foamable resin composition may further contain polyolefin other than the silane-grafted polyolefin. These may be used individually by 1 type, or may use 2 or more types together.

Moreover, the foamable resin composition may further contain a rubber component. Rubber components include ethylene/propylene/nonconjugated diene copolymer rubber (EPDM), styrene/ethylene/butylene/styrene copolymer (SEBS), styrene/butadiene rubber (SBR), butadiene rubber (BR), and Nitrile rubber (NBR) may be mentioned. These may be used individually by 1 type, or may use 2 or more types together.

Moreover, the foamable resin composition may further contain a nucleating agent. Nucleating agents include zinc oxide, calcium carbonate, and silica. These may be used individually by 1 type, or may use 2 or more types together. By using a nucleating agent, the foam cell diameter can be made fine.

Moreover, the foamable resin composition may further contain an antioxidant, a lubricant, a metal deactivator, and a filler. These may be used individually by 1 type, or may use 2 or more types together. Antioxidants include phenol antioxidants, amine antioxidants, and phosphorus antioxidants. Lubricants include hydrocarbon-based lubricants, ester-based lubricants, and fatty acid-based lubricants. Fillers include light calcium carbonate, heavy calcium carbonate, mica, pentonite, zeolite, hydrated lime, kaolin, and diatomaceous earth.

As described above, the foamable resin composition may further contain polyolefins other than the silane-grafted polyolefin. In addition, the chemical foaming agent (the composite foaming agent (A) or the composite foaming agent (B)) may be blended into the foamable resin composition as a masterbatch. Thus, other polyolefins may be included in such masterbatches, for example, along with chemical blowing agents. The other polyolefin is preferably contained in an amount of less than 10 parts by mass with respect to 100 parts by mass of the polyolefin before the silane-grafted polyolefin.

The rubber component, the nucleating agent, the antioxidant, the lubricant, the metal deactivator, and the filler may be blended during kneading for silane grafting the polyolefin. Moreover, the crosslinking catalyst may not be blended during kneading (when preparing the precursor composition), but may be blended when preparing the foamable resin composition.

The expandable resin composition is subjected to silane cross-linking and foaming to obtain a foamed cross-linked polyolefin insulating layer, but the conditions for the above-mentioned silane cross-linking and foaming are not particularly limited as long as a foamed cross-linked polyolefin insulating layer can be obtained. For example, a foamable resin composition containing a precursor composition containing a silane-grafted polyolefin, a chemical blowing agent, and optionally other components is prepared, and silane-crosslinked and foamed to achieve foam-crosslinking. A polyolefin insulating layer is obtained. Specifically, the precursor composition, the chemical foaming agent, and, if necessary, other components are extruded using an extruder (for example, a screw extruder), and the outer circumference of the conductor 11 is extruded in a temperature range of 190 to 210 ° C. A foamed cross-linked polyolefin insulation layer is obtained by coating extrusion. At this time, due to the action of H ₂ O in the air and a crosslinking catalyst, a silane-crosslinked polyolefin having siloxane bonds as crosslinking sites is produced from the silane-grafted polyolefin. Silane cross-linking is superior to other cross-linking methods in terms of molding temperature (decomposition temperature).

The insulating layer 12 has an expansion rate of 5% or more and 30%. In this specification, the foaming ratio is a value calculated from the specific gravity ratio before foaming and after foaming. When the foaming rate is within the above range, cost, heat deformation and tensile strength are well balanced. Moreover, peeling work can be facilitated. The foaming rate can be adjusted, for example, by the amount of chemical blowing agent.

The insulating layer 12 usually has a foam cell diameter of 150 μm or less. In this specification, the foamed cell diameter is a value obtained by observing a cross section of an insulator with a microscope. When the foam cell diameter is within the above range, it is possible to prevent deterioration of physical properties of the foamable resin composition when forming the insulating layer. Moreover, peeling work can be facilitated. If the foamed cell diameter is too large beyond the above range, there is a concern that the properties (mechanical and electrical) of the foam may deteriorate. Foam cell size can be adjusted, for example, through the use of nucleating agents.

The insulating layer 12 normally has a tensile strength of 10 MPa or more and 14 MPa or less. Tensile strength can be adjusted, for example, by changing the foaming rate and foam cell diameter.

Sheath 13 is formed from a material such as polyvinyl chloride or polyethylene. The sheath 13 is formed, for example, by extruding a material so as to cover the outer circumference of the insulating layer 12 using an extruder or the like. The thickness of the sheath 13 is not particularly limited, but is, for example, 1.5 mm or more and 2.0 mm or less.

Specifically, the cable 10 is preferably a cable whose polyolefin contains polyethylene and which is used for circuits of 600 V or less. In other words, it is preferable that the insulating layer 12 is a foamed crosslinked polyolefin layer containing crosslinked polyethylene, and that the cable is used for a circuit of 600 V or less. More specifically, it is preferably a cable (600V CE, 600V CE/F, etc.) specified by JIS C 3605:2002.

FIG. 2 is a cross-sectional view of another example of a cable according to an embodiment; In FIG. 2, another insulating layer 14 is further provided between the insulating layer 12 and the sheath 13 (outer periphery of the insulating layer 12). Also in this case, the insulating layer 12 is adjacent to the conductor 11, and discoloration of the conductor 11 can be suppressed. The other insulating layer 14 is preferably a non-foaming layer formed from a non-foaming resin composition containing no foaming agent from the viewpoint of electrical properties and heat resistance properties. Furthermore, the cable according to the embodiment may have two or more layers of other insulating layers 14 between the insulating layer 12 and the sheath 13 (outer circumference of the insulating layer 12). When two or more other insulating layers 14 are provided, the layer (outermost layer) adjacent to the sheath 13 among the other insulating layers 14 is preferably a non-foamed layer from the viewpoint of electrical properties and heat resistance properties. preferable.

Moreover, although the cable according to the above-described embodiment is a single-core cable, it may be a multi-core cable. Furthermore, the cables according to the above-described embodiments may further have other configurations included in normal cables. For example, a shielding layer may be formed or may have inclusions.

Further, in the cable according to the above-described embodiment, the insulating layer 12 is a foamed crosslinked polyolefin layer containing silane-crosslinked polyolefin, but it may be a foamed crosslinked polyolefin layer containing polyolefin crosslinked by another crosslinking method. . That is, a cable according to an embodiment is a cable having a conductor, an insulating layer provided on the outer circumference of the conductor, and a sheath provided on the outer circumference of the insulating layer, wherein the insulating layer is made of polyolefin and chemical A foamed crosslinked polyolefin insulating layer obtained using a blowing agent, wherein the chemical blowing agent is a composite blowing agent (A) containing azodicarbonamide and sodium hydrogen carbonate, or azodicarbonamide and 4,4 It is a composite foaming agent (B) containing '-oxybis(benzenesulfonylhydrazide), and the chemical foaming agent is used in an amount of 0.1 parts by mass or more and 2.0 parts by mass or less with respect to 100 parts by mass of the polyolefin. The compounding ratio of azodicarbonamide to sodium hydrogencarbonate in the composite foaming agent (A) is 1/9 or more and 9/1 or less in mass ratio, and the composite foaming agent (B) contains 4, The blending ratio of azodicarbonamide to 4′-oxybis(benzenesulfonylhydrazide) is 1/9 or more and 9/1 or less in mass ratio, and the insulating layer has an expansion rate of 5% or more and 30% or less. good. Polyolefins are cross-linked, for example by chemical cross-linking or electron beam cross-linking. Also in this case, the specific examples of the polyolefin and the chemical foaming agent, the preferred range, etc. are as described above.

<Cable manufacturing method>
A method for manufacturing a cable according to an embodiment is a method for manufacturing a cable having a conductor, an insulating layer provided on the outer periphery of the conductor, and a sheath provided on the outer periphery of the insulating layer, wherein the outer periphery of the conductor and silane-crosslinking and foaming a foamable resin composition containing a silane-grafted polyolefin and a chemical foaming agent to provide the insulating layer, which is a foamed crosslinked polyolefin insulating layer, wherein the chemical foaming agent is A composite blowing agent (A) containing azodicarbonamide and sodium hydrogencarbonate, or a composite blowing agent (B) containing azodicarbonamide and 4,4'-oxybis(benzenesulfonylhydrazide), wherein the foaming The flexible resin composition contains the chemical foaming agent in an amount of 0.1 parts by mass or more and 2.0 parts by mass or less with respect to 100 parts by mass of the polyolefin before the silane graft, and the composite The compounding ratio of azodicarbonamide to sodium hydrogencarbonate in the system blowing agent (A) is 1/9 or more and 9/1 or less in mass ratio, and the composite system blowing agent (B) is 4,4'-oxybis The mixing ratio of azodicarbonamide to (benzenesulfonylhydrazide) is 1/9 or more and 9/1 or less in mass ratio, and the insulating layer has an expansion rate of 5% or more and 30% or less. Details such as the step of providing the insulating layer are as described in the cable according to the embodiment.

In addition, in the cable manufacturing method according to the embodiment described above, silane cross-linking is performed when providing the foamed cross-linked polyolefin layer, but other cross-linking methods may be performed. That is, a method for manufacturing a cable according to an embodiment is a method for manufacturing a cable having a conductor, an insulating layer provided on the outer periphery of the conductor, and a sheath provided on the outer periphery of the insulating layer, wherein the conductor and a step of providing the insulating layer, which is a foamed cross-linked polyolefin insulating layer, on the outer periphery of the polyolefin and a chemical blowing agent, wherein the chemical blowing agent is a composite blowing agent containing azodicarbonamide and sodium hydrogen carbonate ( A), or a composite blowing agent (B) containing azodicarbonamide and 4,4′-oxybis(benzenesulfonylhydrazide), wherein the chemical blowing agent is added in an amount of 0.1 to 100 parts by mass of the polyolefin. It is used in an amount of 1 part by mass or more and 2.0 parts by mass or less, and the compounding ratio of azodicarbonamide to sodium hydrogen carbonate in the composite foaming agent (A) is 1/9 or more and 9/1 or less in mass ratio. and the compounding ratio of azodicarbonamide to 4,4′-oxybis(benzenesulfonylhydrazide) in the composite foaming agent (B) is 1/9 or more and 9/1 or less in mass ratio, and the insulating layer is , the expansion rate may be 5% or more and 30% or less.

<Electric wire>
FIG. 3 is a cross-sectional view of an electric wire (insulated electric wire) according to the embodiment. As shown in FIG. 3, the wire 100 has a conductor 101 and a covering layer, ie, an insulating layer 102 . In other words, the electric wire 100 has a conductor 101 and an insulating layer 102 provided around the conductor 101 .

The conductor 101 and insulating layer 102 are the same as the conductor 11 and insulating layer 12 described for the cable 10 . That is, the electric wire according to the embodiment is the same as the cable according to the embodiment, except that it does not have a sheath. Therefore, the effects obtained in the cable according to the embodiment are similarly obtained in the electric wire according to the embodiment.

Further, the following additional remarks are disclosed with respect to the above-described embodiment.

(Appendix 1) Another insulating layer is further provided on the outer periphery of the insulating layer,
Wires or cables as described above.

(Appendix 2) The polyolefin contains polyethylene and is used in circuits of 600 V or less.
Wires or cables as described above.

(Appendix 3) A method for manufacturing an electric wire or cable having a conductor and an insulating layer provided on the outer periphery of the conductor,
A step of providing the insulating layer, which is a foamed crosslinked polyolefin insulating layer, on the outer periphery of the conductor using polyolefin and a chemical foaming agent,
Said chemical blowing agent is a complex blowing agent (A) comprising azodicarbonamide and sodium hydrogencarbonate, or a complex blowing agent (B ) and
The chemical foaming agent is used in an amount of 0.1 parts by mass or more and 2.0 parts by mass or less with respect to 100 parts by mass of the polyolefin,
In the composite foaming agent (A), the mixing ratio of azodicarbonamide to sodium hydrogen carbonate is 1/9 or more and 9/1 or less by mass,
In the composite foaming agent (B), the blending ratio of azodicarbonamide to 4,4'-oxybis(benzenesulfonylhydrazide) is 1/9 or more and 9/1 or less in mass ratio,
The insulating layer has a foaming rate of 5% or more and 30% or less.
A method of manufacturing an electric wire or cable.

(Appendix 4) A method for manufacturing an electric wire or cable having a conductor and an insulating layer provided on the outer periphery of the conductor,
A step of silane-crosslinking and foaming a foamable resin composition containing a silane-grafted polyolefin and a chemical foaming agent on the outer periphery of the conductor to provide the insulating layer, which is a foamed crosslinked polyolefin insulating layer,
Said chemical blowing agent is a complex blowing agent (A) comprising azodicarbonamide and sodium hydrogencarbonate, or a complex blowing agent (B ) and
The foamable resin composition contains the chemical foaming agent in an amount of 0.1 parts by mass or more and 2.0 parts by mass or less with respect to 100 parts by mass of the polyolefin before the silane-grafted polyolefin,
In the composite foaming agent (A), the mixing ratio of azodicarbonamide to sodium hydrogen carbonate is 1/9 or more and 9/1 or less by mass,
In the composite foaming agent (B), the blending ratio of azodicarbonamide to 4,4'-oxybis(benzenesulfonylhydrazide) is 1/9 or more and 9/1 or less in mass ratio,
The insulating layer has a foaming rate of 5% or more and 30% or less.
A method of manufacturing an electric wire or cable.

[Example]
[Example 1]
100 parts by mass of polyethylene, 1.0 parts by mass of vinyltrimethoxysilane as a silane coupling agent, 0.05 parts by mass of dicumyl peroxide as a radical generator, and 0.08 parts by mass of dibutyltin dilaurate as a cross-linking catalyst were added to a Henschel mixer. and kneaded to obtain a precursor composition. Subsequently, the precursor composition and the foaming agent masterbatch containing the composite foaming agent (A) are fed into the cylinder of the screw extruder, and the foamable resin composition obtained therefrom is extruded into a mold having a cross-sectional area of 14 mm ² . copper wire to form a foamed crosslinked polyolefin insulation layer. Here, in the foamable resin composition, the masterbatch was supplied so that the composite foaming agent (A) was contained in an amount of 0.1 parts by mass with respect to 100 parts by mass of the polyethylene before the silane grafting. The composite foaming agent (A) contained ADCA and sodium hydrogencarbonate, and the mixing ratio of ADCA to sodium hydrogencarbonate was 9/1 by mass. Also, the foamed crosslinked polyolefin insulating layer was extruded to a thickness of 0.9 mm. Thus, a prototype cable was produced.

[Example 2]
In the foamable resin composition, the composite foaming agent (A) is contained in an amount of 1.0 parts by mass with respect to 100 parts by mass of the polyethylene before the silane grafting, except that the masterbatch is supplied. A trial cable was produced in the same manner as in Example 1.

[Example 3]
In the foamable resin composition, the composite foaming agent (A) is contained in an amount of 2.0 parts by mass with respect to 100 parts by mass of the polyethylene before the silane grafting, except that the masterbatch is supplied. A trial cable was produced in the same manner as in Example 1.

[Example 4]
A prototype cable was produced in the same manner as in Example 1, except that a composite foaming agent (A) containing ADCA and sodium hydrogencarbonate and having a mixing ratio of ADCA to sodium hydrogencarbonate of 5/5 by mass was used. made.

[Example 5]
In the foamable resin composition, the composite foaming agent (A) is contained in an amount of 1.0 parts by mass with respect to 100 parts by mass of the polyethylene before the silane grafting, except that the masterbatch is supplied. A trial cable was produced in the same manner as in Example 4.

[Example 6]
In the foamable resin composition, the composite foaming agent (A) is contained in an amount of 2.0 parts by mass with respect to 100 parts by mass of the polyethylene before the silane grafting, except that the masterbatch is supplied. A trial cable was produced in the same manner as in Example 4.

[Example 7]
A prototype cable was produced in the same manner as in Example 1, except that a composite foaming agent (A) containing ADCA and sodium hydrogen carbonate and having a mixing ratio of ADCA to sodium hydrogen carbonate of 1/9 by mass was used. made.

[Example 8]
In the foamable resin composition, the composite foaming agent (A) is contained in an amount of 1.0 parts by mass with respect to 100 parts by mass of the polyethylene before the silane grafting, except that the masterbatch is supplied. A prototype cable was produced in the same manner as in Example 7.

[Example 9]
In the foamable resin composition, the composite foaming agent (A) is contained in an amount of 2.0 parts by mass with respect to 100 parts by mass of the polyethylene before the silane grafting, except that the masterbatch is supplied. A prototype cable was produced in the same manner as in Example 7.

[Example 10]
100 parts by mass of polyethylene, 1.0 parts by mass of vinyltrimethoxysilane as a silane coupling agent, 0.05 parts by mass of dicumyl peroxide as a radical generator, and 0.08 parts by mass of dibutyltin dilaurate as a cross-linking catalyst were added to a Henschel mixer. and kneaded to obtain a precursor composition. Subsequently, the precursor composition and the foaming agent masterbatch containing the composite foaming agent (B) are fed into the cylinder of the screw extruder, and the foamable resin composition obtained therefrom is extruded into a mold having a cross-sectional area of 14 mm ² . copper wire to form a foamed crosslinked polyolefin insulation layer. Here, in the foamable resin composition, the masterbatch was supplied so that the composite foaming agent (B) was contained in an amount of 0.1 parts by mass with respect to 100 parts by mass of the polyethylene before the silane grafting. The composite foaming agent (B) contained ADCA and OBSH, and the blending ratio of ADCA to OBSH was 9/1 by mass. Also, the foamed crosslinked polyolefin insulating layer was extruded to a thickness of 0.9 mm. Thus, a prototype cable was produced.

[Example 11]
In the foamable resin composition, the composite foaming agent (B) is contained in an amount of 1.0 parts by mass with respect to 100 parts by mass of the polyethylene before the silane grafting, except that the masterbatch was supplied. A prototype cable was fabricated in the same manner as in Example 10.

[Example 12]
In the foamable resin composition, the composite foaming agent (B) is contained in an amount of 2.0 parts by mass with respect to 100 parts by mass of the polyethylene before the silane grafting, except that the masterbatch is supplied. A prototype cable was fabricated in the same manner as in Example 10.

[Example 13]
A prototype cable was produced in the same manner as in Example 10, except that a composite foaming agent (B) containing ADCA and OBSH and having a blending ratio of ADCA to OBSH of 5/5 by mass was used.

[Example 14]
In the foamable resin composition, the composite foaming agent (B) is contained in an amount of 1.0 parts by mass with respect to 100 parts by mass of the polyethylene before the silane grafting, except that the masterbatch was supplied. A prototype cable was fabricated in the same manner as in Example 13.

[Example 15]
In the foamable resin composition, the composite foaming agent (B) is contained in an amount of 2.0 parts by mass with respect to 100 parts by mass of the polyethylene before the silane grafting, except that the masterbatch is supplied. A prototype cable was fabricated in the same manner as in Example 13.

[Example 16]
A prototype cable was produced in the same manner as in Example 10, except that a composite foaming agent (B) containing ADCA and OBSH and having a blending ratio of ADCA to OBSH of 1/9 by mass was used.

[Example 17]
In the foamable resin composition, the composite foaming agent (B) is contained in an amount of 1.0 parts by mass with respect to 100 parts by mass of the polyethylene before the silane grafting, except that the masterbatch was supplied. A prototype cable was fabricated in the same manner as in Example 16.

[Example 18]
In the foamable resin composition, the composite foaming agent (B) is contained in an amount of 2.0 parts by mass with respect to 100 parts by mass of the polyethylene before the silane grafting, except that the masterbatch is supplied. A prototype cable was fabricated in the same manner as in Example 16.

[Comparative Example 1]
The procedure of Example 1 was repeated except that a composite foaming agent (A′) containing ADCA and sodium hydrogencarbonate and having a blending ratio of ADCA to sodium hydrogencarbonate of 9.5/0.5 by mass was used. Then, a prototype cable was produced.

[Comparative Example 2]
In the foamable resin composition, with respect to 100 parts by mass of polyethylene before the Silang graft, the composite foaming agent (A ') is contained in an amount of 1.0 parts by mass, except that the masterbatch is supplied, A trial cable was produced in the same manner as in Comparative Example 1.

[Comparative Example 3]
In the foamable resin composition, with respect to 100 parts by mass of the polyethylene before the silane grafting, the composite foaming agent (A ') was supplied in an amount of 2.0 parts by mass, except that the masterbatch was supplied. A trial cable was produced in the same manner as in Comparative Example 1.

[Comparative Example 4]
The procedure of Example 1 was repeated except that a composite foaming agent (A') containing ADCA and sodium hydrogencarbonate and having a blending ratio of ADCA to sodium hydrogencarbonate of 0.5/9.5 by mass was used. Then, a prototype cable was produced.

[Comparative Example 5]
In the foamable resin composition, with respect to 100 parts by mass of polyethylene before the Silang graft, the composite foaming agent (A ') is contained in an amount of 1.0 parts by mass, except that the masterbatch is supplied, A trial cable was produced in the same manner as in Comparative Example 4.

[Comparative Example 6]
In the foamable resin composition, with respect to 100 parts by mass of the polyethylene before the silane grafting, the composite foaming agent (A ') was supplied in an amount of 2.0 parts by mass, except that the masterbatch was supplied. A trial cable was produced in the same manner as in Comparative Example 4.

[Comparative Example 7]
A prototype cable was produced in the same manner as in Example 10, except that a composite foaming agent (B') containing ADCA and OBSH and having a blending ratio of ADCA to OBSH of 9.5/0.5 by mass was used. was made.

[Comparative Example 8]
In the foamable resin composition, with respect to 100 parts by mass of the polyethylene before the silane grafting, the composite foaming agent (B ') was supplied in an amount of 1.0 parts by mass, except that the masterbatch was supplied. A trial cable was produced in the same manner as in Comparative Example 7.

[Comparative Example 9]
In the foamable resin composition, with respect to 100 parts by mass of the polyethylene before the silane grafting, the composite foaming agent (B') is contained in an amount of 2.0 parts by mass, except that the masterbatch is supplied, A trial cable was produced in the same manner as in Comparative Example 7.

[Comparative Example 10]
A prototype cable was produced in the same manner as in Example 10, except that a composite foaming agent (B') containing ADCA and OBSH and having a blending ratio of ADCA to OBSH of 0.5/9.5 by mass was used. was made.

[Comparative Example 11]
In the foamable resin composition, with respect to 100 parts by mass of the polyethylene before the silane grafting, the composite foaming agent (B ') was supplied in an amount of 1.0 parts by mass, except that the masterbatch was supplied. A trial cable was produced in the same manner as in Comparative Example 10.

[Comparative Example 12]
In the foamable resin composition, with respect to 100 parts by mass of the polyethylene before the silane grafting, the composite foaming agent (B') is contained in an amount of 2.0 parts by mass, except that the masterbatch is supplied, A trial cable was produced in the same manner as in Comparative Example 10.

The details of each component used above are as follows.
Polyethylene (manufactured by NUC Co., Ltd., NUCG-5130)
Masterbatch containing ADCA (manufactured by Eiwa Kasei Kogyo Co., Ltd., Vinihole AC#LQ), decomposition temperature: 200 to 210 ° C.
Masterbatch containing sodium hydrogen carbonate (manufactured by Eiwa Kasei Kogyo Co., Ltd., FE-507), decomposition temperature: 140 to 170 ° C.
Masterbatch containing OBSH (manufactured by Eiwa Kasei Kogyo Co., Ltd., Neo Cellvon N#5000), decomposition temperature: 155 to 165 ° C.

[evaluation]
The evaluation method and evaluation criteria are as follows.
A foamed cell diameter of 150 μm or less is evaluated as ◯ (passed), and a foamed cell diameter of more than 150 μm is evaluated as x (failed).
A heat deformation test (heat resistance) was measured according to JIS C 3005:2014. ○ indicates 40% or less, and x indicates more than 40%.
Regarding discoloration of the conductor, the presence or absence of discoloration of the conductor was examined before and after the heat deformation test. A case of no discoloration is indicated by ◯, and a case of discoloration is indicated by X.
Regarding the cost, the case where the foaming rate is 5% or more is rated as ◯, and the case where the foaming rate is less than 5% is rated as x.
In the comprehensive judgment, ◯ is given when all the evaluation criteria are satisfied, and x is given when one or more evaluation criteria are not satisfied.
Table 1 shows the evaluation results. From Table 1, it can be seen that the prototype cables of Examples are excellent in foam properties (mechanical and electrical), heat resistance and cost, and discoloration of the metal (conductor) is suppressed.

10 Cable 100 Electric Wires 11, 101 Conductors 12, 102 Insulating Layer 13 Sheath

Claims (5)

An electric wire or cable having a conductor and an insulating layer provided on the outer periphery of the conductor,
The insulating layer is a foamed crosslinked polyolefin insulating layer obtained by using polyolefin and a chemical foaming agent,
Said chemical blowing agent is a complex blowing agent (A) comprising azodicarbonamide and sodium hydrogencarbonate, or a complex blowing agent (B ) and
The chemical foaming agent is used in an amount of 0.1 parts by mass or more and 2.0 parts by mass or less with respect to 100 parts by mass of the polyolefin,
In the composite foaming agent (A), the mixing ratio of azodicarbonamide to sodium hydrogen carbonate is 1/9 or more and 9/1 or less by mass,
In the composite foaming agent (B), the blending ratio of azodicarbonamide to 4,4'-oxybis(benzenesulfonylhydrazide) is 1/9 or more and 9/1 or less in mass ratio,
The insulating layer has a foaming rate of 5% or more and 30% or less.
wire or cable. An electric wire or cable having a conductor and an insulating layer provided on the outer periphery of the conductor,
The insulation layer is a foamed crosslinked polyolefin insulation layer obtained by silane crosslinking and foaming an expandable resin composition containing a silane-grafted polyolefin and a chemical foaming agent,
Said chemical blowing agent is a complex blowing agent (A) comprising azodicarbonamide and sodium hydrogencarbonate, or a complex blowing agent (B ) and
The foamable resin composition contains the chemical foaming agent in an amount of 0.1 parts by mass or more and 2.0 parts by mass or less with respect to 100 parts by mass of the polyolefin before the silane-grafted polyolefin,
In the composite foaming agent (A), the mixing ratio of azodicarbonamide to sodium hydrogen carbonate is 1/9 or more and 9/1 or less by mass,
In the composite foaming agent (B), the blending ratio of azodicarbonamide to 4,4'-oxybis(benzenesulfonylhydrazide) is 1/9 or more and 9/1 or less in mass ratio,
The insulating layer has a foaming rate of 5% or more and 30% or less.
wire or cable. The foamable resin composition further contains at least one nucleating agent selected from zinc oxide, calcium carbonate, and silica.
The wire or cable according to claim 2. The polyolefin contains at least one selected from polyethylene, polypropylene, ethylene-ethyl acrylate copolymer, ethylene-methyl acrylate copolymer, and ethylene-vinyl acetate copolymer,
The wire or cable according to any one of claims 1-3. The insulating layer has a foam cell diameter of 150 μm or less,
The wire or cable according to any one of claims 1-4.

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