Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
  • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
  • H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
  • H01B3/44—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins
  • H01B3/441—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins from alkenes

Definitions

• the present invention relates to an electric wire coated with an insulating material containing a polymer whose main component is ethylene, and more specifically, to an electric wire coated with an insulating material that has excellent electrical resistance characteristics and mechanical strength, using an insulating material containing a polymer whose main component is ethylene, which has excellent extrusion processability.
• Patent Document 1 Polyethylene has traditionally been widely used as an insulating material for electric wires, and its excellent electrical insulation properties have been highly praised. It has also been proposed to use polyethylene produced using metallocene catalysts as an insulating material (Patent Document 1, Patent Document 2).
• the object of the present invention is to solve the problems associated with the conventional technology as described above, and to provide an electric wire having a coating layer with excellent electrical resistance characteristics, mechanical strength, and a good appearance by using an insulating material containing a polymer mainly composed of ethylene, which has excellent extrusion processability.
• the present invention relates to an electric wire in which a conductor or a conductor shielding layer is covered with an insulating material containing a polymer mainly composed of ethylene, and the polymer mainly composed of ethylene satisfies the following requirements (a) to (e).
• the density, measured in accordance with JIS K 6922, is 900 to 925 kg/ m3 .
• the melt flow rate (MFR) measured in accordance with JIS K 6921 temperature: 190° C., load: 21.18 N
• MFR melt flow rate measured in accordance with JIS K 6921 (temperature: 190° C., load: 21.18 N) is 10 to 25 g/10 min.
• the volume resistivity (2 mm thick pressed sheet) measured in accordance with ASTM D257:2007 is 1.0 ⁇ 10 16 ⁇ cm or more.
• the shear viscosity at a shear rate of 12.2 (1/s) measured using a capillary rheometer is 300 (Pa ⁇ s) or more and 8,000 (Pa ⁇ s) or less, and the shear viscosity at a shear rate of 2,432 (1/s) is 30 (Pa ⁇ s) or more and 220 (Pa ⁇ s) or less.
• the insulating material may or may not contain a cross-linking agent.
• the surface of the coating layer made of the insulating material becomes smooth and the coating layer has even better mechanical strength, abrasion resistance, heat resistance, etc.
• the present invention makes it possible to provide an electric wire made of an insulating material containing a polymer mainly composed of ethylene, which has excellent extrusion processability, and which has excellent electrical resistance characteristics, mechanical strength, and a coating layer with a good appearance. Furthermore, by utilizing these characteristics, it is possible to provide a flame-retardant eco-friendly electric wire, particularly one with a coating layer that contains an inorganic flame retardant.
• the present invention relates to an electric wire in which an insulating material containing a polymer mainly composed of ethylene is extrusion coated onto a conductor or a conductor shielding layer such as a semiconducting layer, and the configuration thereof will be described below.
• the polymers containing ethylene as a main component used in the present invention include ethylene homopolymers and ethylene- ⁇ -olefin copolymers, and one or more of these may be used as necessary depending on the application of the electric wire.
• Polymers containing ethylene as a main component are suitable, which contain 50% by weight, preferably 60% by weight or more of ethylene, and among these, ethylene- ⁇ -olefin copolymers are more suitable.
• the ethylene/ ⁇ -olefin copolymer is formed from a copolymer of ethylene as a main component and an ⁇ -olefin having 3 to 20 carbon atoms.
• Specific examples of the ⁇ -olefin having 3 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, and 1-dodecene.
• the ethylene- ⁇ -olefin copolymer may contain at least a part of the constituent monomers that are biomass-derived monomers (ethylene, ⁇ -olefin).
• the monomers that constitute the copolymer may be only biomass-derived monomers, or may contain both biomass-derived monomers and fossil fuel-derived monomers.
• the biomass-derived monomer is a monomer made from any renewable natural raw material, such as plant-derived or animal-derived, including fungi, yeast, algae, and bacteria, and its residue, and contains about 10 -12 of 14 C isotope as carbon, and has a biomass carbon concentration (pMC) of about 100 (pMC) measured in accordance with ASTM D6866.
• the biomass-derived monomer is obtained by a conventionally known method.
• the monomers that constitute the ethylene- ⁇ -olefin copolymer according to the present invention contain biomass-derived monomers from the viewpoint of reducing the environmental load (mainly reducing greenhouse gases). If the polymer production conditions, such as the polymerization catalyst, polymerization process, and polymerization temperature, are the same, even if the raw material monomer contains a biomass-derived monomer, the molecular structure, other than the inclusion of 14C isotopes at a ratio of about 10 -12 to 10 -14 , is the same as that of an ethylene- ⁇ -olefin copolymer made of a fossil fuel-derived monomer. Therefore, the performance is said to be the same.
• the ethylene- ⁇ -olefin copolymer according to the present invention may contain at least a part of the constituent monomers that are derived from chemical recycling (ethylene, ⁇ -olefin).
• the monomers that constitute the copolymer may be only monomers derived from chemical recycling, or may contain monomers derived from chemical recycling and monomers derived from fossil fuels and/or monomers derived from biomass.
• the monomers derived from chemical recycling are obtained by a conventionally known method. It is preferable that the monomers that constitute the ethylene- ⁇ -olefin copolymer according to the present invention contain monomers derived from chemical recycling from the viewpoint of reducing the environmental load (mainly reducing waste).
• the monomers derived from chemical recycling are monomers that are obtained by depolymerizing or pyrolyzing polymers such as waste plastics back to monomer units such as ethylene, and monomers that are produced using such monomers as raw materials. Therefore, if the polymer production conditions such as the polymerization catalyst, polymerization process, and polymerization temperature are the same, the molecular structure is the same as that of an ethylene- ⁇ -olefin copolymer made of monomers derived from fossil fuels. Therefore, the performance is said to be the same.
• the ethylene content in the ethylene/ ⁇ -olefin copolymer is usually 93 to 99 mol %, preferably 94 to 98 mol %, and the content of the comonomer ⁇ -olefin is usually 1 to 7 mol %, preferably 2 to 6 mol %.
• the ethylene and ⁇ -olefin contents can be measured by 13 C-NMR.
• the composition of the ethylene/ ⁇ -olefin copolymer is usually determined by measuring the C-NMR spectrum of a sample prepared by uniformly dissolving about 200 mg of the copolymer in 1 ml (milliliter) of hexachlorobutadiene in a sample tube of 10 mm ⁇ under the following measurement conditions: measurement temperature 120° C., measurement frequency 25.05 MHz, spectrum width 1500 Hz, pulse repetition time 4.2 sec, pulse width 6 ⁇ sec.
• the polymer containing ethylene as a main component for use in the present invention is characterized in that it satisfies the following requirements (a), (b), (c), (d) and (e).
• the density measured in accordance with JIS K 6922 is 900 to 925 kg/ m3 .
• 902 to 920 kg/m 3 is preferable, 903 to 915 kg/m 3 is more preferable, and 904 to 913 kg/m 3 is even more preferable.
• melt flow rate (MFR) measured in accordance with JIS K 6921 is 10 to 25 g/10 min. Among these, 10 to 20 g/10 min is preferable. More preferably, it is 10 to 15 g/10 min.
• the volume resistivity (2 mm thick press sheet) is 1.0 ⁇ 10 16 ⁇ cm or more.
• the lower limit is 3.0 ⁇ 10 16 ⁇ cm or more. More preferably, the lower limit is 5.0 ⁇ 10 16 ⁇ cm or more. Even more preferably, the lower limit is 8.0 ⁇ 10 16 ⁇ cm or more.
• the upper limit is not particularly limited in terms of performance, but since the polymer is mainly composed of ethylene, it is practically 1.0 ⁇ 10 19 ⁇ cm or less.
• the volume resistivity When the volume resistivity is high, the insulating properties of the electric wire are high, and when the volume resistivity is low, the insulating properties are low. It is generally known that the volume resistivity of a material is high when it does not contain a conductor such as a metal. Therefore, even in an ethylene-based polymer that is polymerized using a catalyst containing a metal element and in which a trace amount of the catalyst remains, it is presumed that the volume resistivity changes depending on the type of metal in the catalyst.
• the shear viscosity at a shear rate of 12.2 (1/s) measured using a capillary rheometer is 300 (Pa ⁇ s) or more and 8,000 (Pa ⁇ s) or less, and the shear viscosity at a shear rate of 2,432 (1/s) is 30 (Pa ⁇ s) or more and 220 (Pa ⁇ s) or less.
• the preferred range is a shear viscosity of 400 (Pa ⁇ s) or more and 5000 (Pa ⁇ s) or less at a shear rate of 12.2 (1/s), and a shear viscosity of 40 (Pa ⁇ s) or more and 200 (Pa ⁇ s) or less at a shear rate of 2432 (1/s).
• more preferred ranges of shear viscosity at a shear rate of 12.2 (1/s) are 500 (Pa ⁇ s) or more and 4000 (Pa ⁇ s) or less, and the shear viscosity at a shear rate of 2432 (1/s) is 50 (Pa ⁇ s) or more and 180 (Pa ⁇ s) or less.
• even more preferred ranges of shear viscosity at a shear rate of 12.2 (1/s) are 500 (Pa ⁇ s) or more and 4000 (Pa ⁇ s) or less, and the shear viscosity at a shear rate of 2432 (1/s) is 50 (Pa ⁇ s) or more and 120 (Pa ⁇ s) or less.
• more preferred ranges are a shear viscosity of 500 (Pa ⁇ s) or more and 2000 (Pa ⁇ s) or less at a shear rate of 12.2 (1/s), and a shear viscosity of 60 (Pa ⁇ s) or more and 160 (Pa ⁇ s) or less at a shear rate of 2432 (1/s).
• particularly preferred ranges for this range are a shear viscosity of 500 (Pa ⁇ s) or more and 2000 (Pa ⁇ s) or less at a shear rate of 12.2 (1/s), and a shear viscosity of 60 (Pa ⁇ s) or more and 100 (Pa ⁇ s) or less at a shear rate of 2432 (1/s).
• the measured values tend to vary widely, so it is preferable to use data measured on a resin strand with a smooth surface.
• any part of the product that has a higher filler concentration than the average filler concentration will not have enough resin present, resulting in low tensile elongation and low tensile strength, and as a result will be a weak spot that breaks easily.
• the coating layer of the present invention contains a filler, its good dispersibility results in improved tensile strength of the coating layer, which is a molded product.
• a low viscosity at high shear rate tends to suppress roughening of the surface of the coating layer when it is molded, and as a result, the molding speed can be increased without roughening. Therefore, it is difficult to achieve both improved strength, which depends on melt-kneading with fillers, etc., and prevention of roughening of the coating layer during high-speed molding, by simply adjusting the MFR.
• the 50% crack generation time ( F50 ) in the environmental stress rupture resistance test (ESCR test, 3 mm thick press sheet, test temperature 65°C) according to ASTM D1693 is 10 hours or more. More preferably, it is 30 hours or more. Even more preferably, it is 100 hours or more. Furthermore, it is 200 hours or more. In terms of practical measurement time, the upper limit is generally 1500 hours, and in some cases it is about 1000 hours.
• the present invention uses an insulating material with excellent durability, it is particularly suitable for flame-retardant eco-friendly electric wires containing inorganic flame retardants.
• the environmental stress crack resistance (ESCR test) F50 value is adjusted by the molecular weight, density, and blending amount of the high molecular weight polymer of the ethylene- ⁇ -olefin copolymer, and the F50 value can be increased by increasing the molecular weight of the high molecular weight polymer, increasing its ratio, or decreasing its density.
• polymers having a long chain branching structure such as high pressure LDPE, which has a high melt tension and is easy to process, are considered to have a smaller environmental stress crack resistance F50 value than linear polymers.
• Method for Producing Polymers Containing Ethylene as a Main Component can be produced by adjusting the polymerization conditions using a conventionally known catalyst system so as to obtain a polymer that satisfies the above-mentioned requirements (a) to (e) below.
• the density can be adjusted by changing the ratio of the copolymerization components of the polymer.
• the density increases by decreasing the ratio of the copolymerization components.
• the MFR can be adjusted by adjusting the average molecular weight of the polymer. The higher the average molecular weight, the smaller the MFR.
• Method for producing a polymer mainly composed of ethylene As a method for producing a polymer mainly composed of ethylene, particularly an ethylene- ⁇ -olefin copolymer, there is a method for obtaining the copolymer by multi-stage polymerization such as two-stage polymerization using a conventionally known catalyst system, for example, a single-site catalyst such as a metallocene catalyst.
• the ethylene/ ⁇ -olefin copolymer having the above-mentioned physical properties can be suitably produced by supplying ethylene and an ⁇ -olefin having 3 to 20 carbon atoms to a polymerization system using, for example, bis(n-propylcyclopentadienyl)zirconium dichloride, bis(n-butylcyclopentadienyl)zirconium dichloride, bis(1-methyl-3-n-propylcyclopentadienyl)zirconium dichloride, or bis(1-methyl-3-n-butylcyclopentadienyl)zirconium dichloride, which contains a ligand having a cyclopentadienyl skeleton, as component (a), which is a transition metal compound of the polymerization catalyst.
• component (a) which is a transition metal compound of the polymerization catalyst.
• component (a) In the production of ethylene- ⁇ -olefin copolymers, it is common to use the above component (a) in combination with component (b) (organoaluminum oxy compound), carrier (c), and, if necessary, component (d) (organoaluminum compound), etc.
• the organoaluminum oxy compound may be a conventionally known benzene-soluble organoaluminum oxy compound, or may be a benzene-insoluble organoaluminum oxy compound as disclosed in JP-A-2-276807.
• the organoaluminum oxy compound may be used alone or in combination of two or more kinds.
• a specific example is methylaluminoxane.
• the carrier (iii) used is an inorganic or organic compound, and a granular or fine particle solid having a particle size of 10 to 300 ⁇ m, preferably 20 to 200 ⁇ m is used.
• the inorganic carrier is preferably a porous oxide, specifically SiO 2 , Al 2 O 3 , MgO, ZrO 2 , TiO 2 , Sb 2 O 3 , CaO, ZnO, BaO, ThO 2 , etc., or a mixture thereof, such as SiO 2 -MgO, SiO 2 -Al 2 O 3 , SiO 2 -TiO 2 , SiO 2 -V 2 O 5 , SiO 2 -Cr 2 O 3 , SiO 2 -TiO 2 -MgO, etc. are exemplified. Among these, those containing at least one component selected from the group consisting of SiO 2 and Al 2 O 3 as the main component are preferred.
• a carrier that is preferably used has a specific surface area of 50 to 1000 m2 /g, preferably 100 to 700 m2 /g, and a pore volume of 0.3 to 2.5 cm2 /g.
• the carrier (C) may be calcined at 100 to 1000°C, preferably 150 to 700°C, if necessary, before use.
• the usable carrier (iii) include granular or fine particle solids of organic compounds having a particle size of 10 to 300 ⁇ m.
• organic compounds include (co)polymers mainly composed of ⁇ -olefins having 2 to 14 carbon atoms, such as ethylene, propylene, 1-butene, and 4-methyl-1-pentene, and polymers or copolymers mainly composed of vinylcyclohexane and styrene.
• Component (IV) Organoaluminum Compound Component (IV) an organoaluminum compound which is added as necessary can be exemplified by compounds represented by the following general formula (I).
• R 1 (n) AlX (3-n) ⁇ (I) (In the formula, R 1 represents a hydrocarbon group having 1 to 12 carbon atoms, X represents a halogen atom or a hydrogen atom, and n is 1 to 3.)
• R 1 is, for example, an alkyl group, a cycloalkyl group, or an aryl group, and specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an isobutyl group, a pentyl group, a hexyl group, an octyl group, and the like. Examples of such groups include cyclopentyl, cyclohexyl, phenyl, and tolyl groups.
• organoaluminum compounds include the following compounds: Trialkylaluminums such as trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, trioctylaluminum, and tri-2-ethylhexylaluminum; alkenylaluminums such as isoprenylaluminum; and dialkylaluminum halides such as dimethylaluminum chloride, diethylaluminum chloride, diisopropylaluminum chloride, diisobutylaluminum chloride, and dimethylaluminum bromide.
• Trialkylaluminums such as trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, trioctylaluminum, and tri-2-ethylhexylaluminum
• alkenylaluminums such as isopre
• R 1 (n) AlY (3-n) . . . (II) can also be used.
• R 1 represents a hydrocarbon group similar to R 1 in the above general formula (I);
• Y represents -OR 2 group, -OSi(R 3 ) 3 group, -OAl(R 4 ) 2 group, -N(R 5 ) 2 group, -Si(R 6 ) 3 group or -N(R 7 )Al(R 8 ) 2 group;
• n is 1 to 2;
• R 2 , R 3 , R 4 and R 8 represent methyl, ethyl, isopropyl, isobutyl, cyclohexyl, phenyl, etc.;
• R 5 represents a hydrogen atom, methyl, ethyl, isopropyl, phenyl, trimethylsilyl, etc.;
• R 6 and R 7 represent methyl, e
• R 1 (n) Al(OR 2 ) (3-n) for example, dimethylaluminum methoxide, diethylaluminum ethoxide, diisobutylaluminum methoxide, etc.; Compounds represented by R 1 (n) Al(OSi(R 3 ) 3 ) (3-n) , for example, Et 2 Al(OSiMe 3 ), (iso-Bu) 2 Al(OSiMe 3 ), (iso-Bu) 2 Al(OSiEt 3 ), etc.; Compounds represented by R 1 (n) Al(OAl(R 4 ) 2 ) (3-n) , for example, Et 2 AlOAlEt 2 , (iso-Bu) 2 AlOAl(iso-Bu) 2 , etc.; Compounds represented by R 1 (n) Al(N(R 5 ) 2 ) (3-n) , for example, Me 2 AlNEt 2 , Et 2 AlNHMe, Me 2 AlN
• Catalyst Preparation Method The polymerization catalyst is prepared, for example, by contacting the above-mentioned components (A), (B), and (C), and, if necessary, (D). The order of contacting the components is arbitrarily selected, but it is preferable to mix and contact the support (C) and component (B), then mix and contact the above-mentioned component (A), and, if necessary, mix and contact the component (D).
• the polymerization catalyst may also be a prepolymerization catalyst obtained by prepolymerizing an olefin such as ethylene in the presence of component (a), component (b), a carrier (c), and, if necessary, component (d).
• a prepolymerization catalyst obtained by prepolymerizing an olefin such as ethylene in the presence of component (a), component (b), a carrier (c), and, if necessary, component (d).
• the prepolymerization can be carried out by introducing an olefin such as ethylene into an inert hydrocarbon solvent in the presence of component (a), component (b), carrier (c), and, if necessary, component (d).
• an olefin such as ethylene
• the prepolymerization catalyst is prepared, for example, by the following method. That is, the carrier (c) is suspended in an inert hydrocarbon. Next, an organoaluminum oxy compound (component (b)) is added to this suspension and reacted for a specified time. The supernatant is then removed and the resulting solid component is resuspended in an inert hydrocarbon. A transition metal compound (component (a)) is added to this system and reacted for a specified time, after which the supernatant is removed to obtain a solid catalyst component. Next, the solid catalyst component obtained above is added to an inert hydrocarbon containing an organoaluminum compound (component (d)), and an olefin such as ethylene is introduced thereto to obtain a prepolymerization catalyst.
• the prepolymerization can be carried out in either a batch system or a continuous system, and can be carried out under reduced pressure, normal pressure or increased pressure. In the prepolymerization, it is desirable to produce a prepolymer having an intrinsic viscosity [ ⁇ ] of 0.2 to 7 (dl/g), preferably 0.5 to 5 (dl/g), measured in decalin at least 135° C. in the presence of hydrogen.
• Polymerization Method The ethylene/ ⁇ -olefin copolymer used in the present invention can be obtained by copolymerizing ethylene with an ⁇ -olefin having 3 to 20 carbon atoms in the presence of the above-mentioned polymerization catalyst or prepolymerization catalyst.
• the copolymerization of ethylene with ⁇ -olefins is carried out in the gas phase or in the liquid phase as a slurry.
• the solvent can be an inert hydrocarbon or the olefin itself.
• inert hydrocarbon solvents used in slurry polymerization include aliphatic hydrocarbons such as butane, isobutane, pentane, hexane, octane, decane, dodecane, hexadecane, and octadecane; alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane, and cyclooctane; aromatic hydrocarbons such as benzene, toluene, and xylene; and petroleum fractions such as gasoline, kerosene, and diesel. Of these inert hydrocarbon media, aliphatic hydrocarbons, alicyclic hydrocarbons, and petroleum fractions are preferred.
• the above-mentioned olefin polymerization catalyst or prepolymerization catalyst is desirably used in an amount of usually 10 -8 to 10 -3 gram atom/liter, preferably 10 -7 to 10 -3 gram atom/liter, in terms of the transition metal atom concentration in the polymerization reaction system.
• an organoaluminum oxy-compound similar to component (ii) and/or an organoaluminum compound similar to component (iv) may be added during polymerization.
• the atomic ratio (Al/M) of the aluminum atom (Al) derived from the organoaluminum oxy-compound and the organoaluminum compound to the transition metal atom (M) derived from the transition metal compound (component (i)) is in the range of 5 to 300, preferably 10 to 200, and more preferably 15 to 150.
• the polymerization temperature is usually in the range of -50 to 100°C, preferably 0 to 90°C, and when performing the gas phase polymerization method, the polymerization temperature is usually in the range of 0 to 120°C, preferably 20 to 100°C.
• the polymerization pressure is usually normal pressure to 100 kg/ cm2 , preferably 2 to 50 kg/ cm2 .
• the polymerization can be carried out in any of batch, semi-continuous and continuous systems, and can also be carried out in multiple stages such as two-stage polymerization.
• the polymer containing ethylene as a main component of the present invention may be blended with various additives such as antioxidants, ultraviolet absorbers, lubricants, nucleating agents, antistatic agents, flame retardants, pigments, dyes, and inorganic or organic fillers, as required.
• Insulating material The insulating material according to the present invention contains a polymer mainly composed of ethylene, and may be composed of only the polymer mainly composed of ethylene, or may be a composition in which other olefin polymers are blended with the polymer.
• the polymer mainly composed of ethylene satisfies the above-mentioned requirements (a) to (e), and therefore has excellent extrusion characteristics, and serves as an excellent insulating material, and can provide an electric wire having a coating layer excellent in electrical resistance characteristics and mechanical strength and good appearance.
• the insulating material of the present invention can contain other polymers such as high-pressure low-density polyethylene, linear low-density polyethylene, high-density polyethylene, polypropylene, EVA, modified polyethylene, etc., as necessary, to the extent that the performance of the electric wire is not impaired.
• high-pressure low-density polyethylene when high-pressure low-density polyethylene is included, its blending ratio is set to 3 to 40% by weight, more preferably 10 to 35% by weight.
• a cross-linking agent can be added to the insulating material, a polymer whose main component is ethylene.
• Suitable cross-linking agents include peroxides and silane compounds.
• peroxides examples include dicumyl peroxide, t-butylcumyl peroxide, 1,3-bis-(t-butylperoxy-isopropyl)benzene, 2,5-dimethyl-2,5-di-(t-butylperoxy)-hexyne-3, 2,5-dimethyl-2,5-di(t-butylperoxy)-hexane, 1-(2-t-butylperoxyisopropyl)-4-isopropylbenzene, and 1-(2-t-butylperoxyisopropyl)-3-isopropylbenzene.
• These peroxides are mixed in an amount of 0.03 to 5 parts by weight, preferably 0.05 to 3 parts by weight, per 100 parts by weight of the insulating material.
• silane compounds examples include vinyltrimethoxysilane and vinyltriethoxysilane. These silane compounds can be used in combination with the peroxides described above, and are mixed in an amount of 0.3 to 5 parts by weight, preferably 0.5 to 3 parts by weight, per 100 parts by weight of the insulating material.
• a crosslinking catalyst can be used in combination, such as di-n-butyltin dilaurate or di-n-octyltin dilaurate.
• the crosslinking reaction can be induced by heat, and when a silane compound is used, the crosslinking reaction can be induced by water.
• the ethylene- ⁇ -olefin copolymer of the present invention can also be crosslinked by exposure to ionizing radiation such as an electron beam.
• the crosslinking method, type and amount of crosslinking agent, and crosslinking conditions can be selected so that the final crosslinking degree is 25% or more, preferably 40% or more.
• Additives such as antioxidants, weather stabilizers, light stabilizers, heat stabilizers, antistatic agents, lubricants, pigments, dyes, nucleating agents, plasticizers, hydrochloric acid absorbers, and flame retardants can be added to the insulating material as needed, provided that the object of the present invention is not impaired.
• flame retardants there are no limitations on the flame retardants that can be added, and organic flame retardants containing halogenated resins can also be added.
• inorganic flame retardants such as magnesium hydroxide and aluminum hydroxide, which are often used in products known as flame-retardant eco-wires, can be used.
• the content of fillers such as inorganic flame retardants in the insulating material is preferably 30% by weight or more and 80% by weight or less.
• the insulating material is a polymer whose main component is ethylene
• a crosslinking agent is blended into the insulating material and the insulating material is crosslinked
• the insulating material layer coated on the conductor or conductor shielding layer changes to a crosslinked structure, improving heat resistance and heat cycle properties.
• the electric wire according to the present invention is produced by extrusion coating an insulating material containing the above-mentioned polymer mainly composed of ethylene onto a conductor or a conductor shielding layer. First, the insulating material is fed to an extrusion coating molding machine, melted, and fed forward of the extruder.
• the insulating material layer may be the outermost layer of the electric wire, or the outside of the insulating material layer may be further coated with another resin or other material.
• the insulating material is a polymer whose main component is ethylene
• it may be used for electric wires in an uncrosslinked state, or a coating layer made of a crosslinked insulating material may be used.
• Crosslinking may be performed using electron beams or ultraviolet light, but it is preferable to use an insulating material containing a crosslinking agent. In this case, the crosslinking process is carried out after the coating layer is formed under the extrusion conditions described above.
• the insulating material is cross-linked by heating to a temperature above the decomposition temperature of the peroxide.
• One method for this is to first mix a composition of a polymer whose main component is ethylene and another olefin polymer with peroxide in an extruder to produce a compound in advance, and then use that compound to coat and heat the wire to produce an electric wire with a cross-linked insulating material.
• the insulating material is cross-linked in the same way by the action of water when the coated molded product is immersed in warm water or left in air.
• a polymer mainly composed of ethylene or a composition of a polymer mainly composed of ethylene and another olefin polymer is first introduced into the hopper of an extruder, while a silane compound, peroxide, and a cross-linking catalyst are continuously injected between the hopper and the extruder, or into the barrel of the extruder, whereby an insulating material in which the silane compound is graft-copolymerized is produced in the extruder and is used to coat the electric wire, and then the coated molded product is immersed in warm water or left in air to produce an electric wire coated with a cross-linked insulating material.
• a silane compound and peroxide are first mixed with an ethylene- ⁇ -olefin copolymer or a composition of an ethylene- ⁇ -olefin copolymer and another ethylene-based polymer to produce a grafted product, which is then added to a crosslinking catalyst master batch and introduced into an extruder to coat the electric wire.
• the coated molded product is then immersed in warm water or left in the air to crosslink the insulating material and produce a coated electric wire.
• the physical properties, capillary flow curves and evaluations were performed according to the following methods. Density (kg/ m3 ) Measurement was performed in accordance with JIS K 6922. Melt flow rate (MFR) (g/10 min, 190° C.) The measurement was performed in accordance with JIS K 6921 at a temperature of 190° C. and a load of 21.18 N. Shear viscosity (Pa ⁇ s) The measurement was carried out using a capillary rheometer under the following conditions.
• the resin strand coming out of the capillary rheometer has significant surface irregularities, such as a diameter variation of 0.5 mm or more depending on the location, the measurement values will vary greatly, so it is preferable to make an evaluation based on the data when the surface is smooth.
• Environmental Stress Crack Resistance (ESCR) Hr.
• the measurement was performed according to a method in accordance with ASTM D 1693. A pressed sheet having a thickness of 3 mm was used. Long-term durability If the E.S.C.R.
• Example 1 An ethylene- ⁇ -olefin copolymer (Evolue SP15151 manufactured by Prime Polymer Co., Ltd.) was fed into a single-screw extruder with a diameter of 100 mm, while a conductor with a diameter of 16 mm was fed into the crosshead die, and a coating operation was continuously performed on the conductor to form a coating layer with a thickness of 2.5 mm. Molding was performed with the cylinder temperature and die temperature of the extruder both set at 200° C. The physical properties of the coating layer of the obtained electric wire were measured, and the results are shown in Table 1. (Comparative Examples 1 to 5) In each comparative example, the same procedure as in Example 1 was carried out except that the polyethylene resin shown below was used. The results are shown in Table 1.
• Comparative Example 1 Elite 5220G manufactured by The Dow Chemical Company Density: 915 (kg/m 3 ), MFR: 3.5 (g/10 minutes, 190°C) Comparative Example 2: SABIC COHERE S100, Density: 915 (kg/m 3 ), MFR: 1 (g/10 minutes, 190°C) Comparative Example 3 Sumikasen G701 manufactured by Sumitomo Chemical Density: 919 (kg/m 3 ), MFR: 6.9 (g/10 minutes, 190°C) Comparative Example 4: Asahi Kasei Santech-LD M2270, Density: 923 (kg/m 3 ), MFR: 7 (g/10 minutes, 190°C) Comparative Example 5 Neozex 25500J manufactured by Prime Polymer, Density: 926 (kg/m 3 ), MFR: 50 (g/10 minutes, 190°C)
• the electric wire of the present invention has excellent extrusion processability of the coating layer, and the coating layer has excellent electrical resistance characteristics and mechanical strength, making it suitable for use as an electric wire in a wide variety of fields.

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