Electric wire

Abstract

The technical problem addressed by the present invention is to provide an electric wire which uses an insulating material containing a polymer having ethylene as the main component and having excellent extrusion processability, and which has a coating layer having excellent resistance characteristics, excellent mechanical strength, and a good appearance. [Solution] An electric wire in which a conductor or a conductor shielding layer is covered with an insulating material containing a polymer having ethylene as the main component, the density of the polymer having ethylene as the main component being within a specific range, the melt flow rate (MFR) being within a specific range, and the volume resistivity (Omega * cm) being within a specific range, the range of shear viscosity (Pa.s) is in a range in which a specific flow curve is formed, and the 50% crack generation time (F50) in an environmental stress crack resistance test (E.S.C.R. Test) is in a specific range.

Description

Technical Field

[0001] The present invention relates to an electric wire coated with an insulating material containing a polymer having ethylene as a main component, and more specifically to an electric wire coated with an insulating material having excellent electrical resistance characteristics and mechanical strength using an insulating material containing a polymer having ethylene as a main component and having excellent extrusion processability. Background Art

[0002] Polyethylene has long been widely used as an insulating material for electric wires, and its excellent electrical insulation properties have been highly praised. Furthermore, proposals have also been made to use polyethylene produced using metallocene catalysts as insulating materials (Patent Documents 1 and 2).

[0003] However, there is a demand for electric wire covering materials that are more excellent in extrusion processability, electrical resistance characteristics, and mechanical strength.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2000-306432

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 2006-312753 Summary of the Invention

[0008] Technical problem to be solved by the invention

[0009] The present invention aims to solve the above-mentioned problems in the prior art and provide an electric wire having a coating layer with excellent electrical resistance characteristics, mechanical strength and good appearance by using an insulating material containing a polymer mainly composed of ethylene and having excellent extrusion processability.

[0010] Technical solutions to technical problems

[0011] That is, the main aspects of the present invention are as follows.

[0012] The present invention relates to an electric wire, characterized in that:

[0013] The conductor or the conductor shielding layer is covered with an insulating material containing a polymer having ethylene as a main component, and the polymer having ethylene as a main component satisfies the following requirements (a) to (e).

[0014] (a) Density measured according to JIS K 6922 is 900 to 925 kg / m 3 .

[0015] (b) The melt flow rate (MFR) measured in accordance with JIS K 6921 (temperature 190° C., load 21.18 N) is 10 to 25 g / 10 minutes.

[0016] (c) The volume resistivity (2 mm thick press sheet) measured according to ASTM D257:2007 is 1.0×10 16 Ω·cm or more.

[0017] (d) The shear viscosity at a shear rate of 12.2 (1 / s) measured using a capillary rheometer is greater than 300 (Pa·s) and less than 8000 (Pa·s), and the shear viscosity at a shear rate of 2432 (1 / s) is greater than 30 (Pa·s) and less than 220 (Pa·s).

[0018] Determination method

[0019] Melt viscosity (flow curve) determination

[0020] Device: Capillary Rheometer "CAPILOGRAPH 1D"

[0021] (Toyo Seiki Co., Ltd.)

[0022] Capillary: L = 30 mm, D = 1 mm, inflow angle = 180°

[0023] Extrusion speed: 1, 2, 5, 10, 20, 50, 100, 200 mm / min

[0024] Measurement temperature: 190°C

[0025] (e) 50% crack initiation time (F) in environmental stress crack resistance according to ASTM D1693 (ESCR test, 3 mm thick pressed sheet, test temperature 65°C) 50 ) is more than 10 hours.

[0026] The insulating material may or may not contain a crosslinking agent. When the insulating material is crosslinked by various methods, the surface of the coating layer formed by the insulating material becomes smoother, and the coating layer can be formed with better mechanical strength, wear resistance, heat resistance, etc.

[0027] Effects of the Invention

[0028] The present invention provides an electric wire having a coating layer formed from an insulating material containing an ethylene-based polymer with excellent extrusion processability, exhibiting excellent electrical resistance and mechanical strength, and having a good appearance. Furthermore, utilizing these properties, it is possible to provide a flame-retardant, environmentally friendly electric wire having a coating layer containing, in particular, an inorganic flame retardant. DETAILED DESCRIPTION

[0029] The present invention relates to an electric wire obtained by extruding and coating an insulating material containing a polymer containing ethylene as a main component on a conductor or a conductor shielding layer such as a semiconductor layer. The structure thereof will be described below.

[0030] Examples of the polymer containing ethylene as a main component used in the present invention include ethylene homopolymers and ethylene-α-olefin copolymers. One or more of these can be used as needed depending on the application of the electric wire.

[0031] Polymers with ethylene as the main component

[0032] Among them, as the polymer containing ethylene as the main component, a polymer having an ethylene content of 50% by weight or more, preferably 60% by weight or more is preferably used, and an ethylene-α-olefin copolymer is more preferably used.

[0033] Ethylene-α-olefin copolymer

[0034] The ethylene-α-olefin copolymer is a copolymer containing ethylene as a main component and an α-olefin having 3 to 20 carbon atoms. Specific examples of the α-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.

[0035] In ethylene-α-olefin copolymers, at least a portion of the monomers may include monomers derived from biomass (ethylene, α-olefin). The monomers that constitute the copolymer may be solely monomers derived from biomass, or may include both monomers derived from biomass and monomers derived from fossil fuels. Biomass-derived monomers refer to monomers formed from all renewable natural raw materials, including fungi, yeast, algae, and bacteria, or animal sources, and their residues, and contain 10 ﹣12 Left-right ratio 14 C isotope, the biomass carbon concentration (pMC) measured according to ASTM D6866 is about 100 (pMC). Monomers derived from biomass can be obtained by existing well-known methods. From the perspective of reducing environmental load (mainly reducing greenhouse gases), it is preferred that the monomers constituting the ethylene-α-olefin copolymer of the present invention contain monomers derived from biomass. If the polymer manufacturing conditions such as the polymerization catalyst, polymerization process, and polymerization temperature are the same, even if the raw material monomers contain monomers derived from biomass, divided by 10 ﹣12 ~10 ﹣14 The ratio of about 14 The molecular structure, excluding the C isotope, is identical to that of ethylene-α-olefin copolymers made from fossil fuel-derived monomers, so the performance remains unchanged.

[0036] In addition, in the ethylene-α-olefin copolymer of the present invention, at least a portion of the constituent monomers may include monomers derived from chemical recycling (ethylene, α-olefin). The monomers constituting the copolymer may be solely monomers derived from chemical recycling, or may include monomers derived from chemical recycling as well as monomers derived from fossil fuels and / or monomers derived from biomass. Monomers derived from chemical recycling can be obtained by conventionally known methods. From the perspective of reducing environmental load (mainly reducing waste), it is preferred that the monomers constituting the ethylene-α-olefin copolymer of the present invention contain monomers derived from chemical recycling. Even if the raw material monomers contain monomers derived from chemical recycling, since monomers derived from chemical recycling are monomers obtained by depolymerizing polymers such as waste plastics and returning them to monomer units such as ethylene through depolymerization and thermal cracking, and monomers produced using these monomers as raw materials, if the polymer production conditions such as the polymerization catalyst, polymerization process, and polymerization temperature are the same, the molecular structure is also the same as that of ethylene-α-olefin copolymers composed of monomers derived from fossil fuels. Therefore, the performance does not change.

[0037] The ethylene content of the ethylene-α-olefin copolymer is usually 93 to 99 mol%, preferably 94 to 98 mol%, and the content of the α-olefin as a comonomer is usually 1 to 7 mol%, preferably 2 to 6 mol%. 13 C-NMR was used for measurement.

[0038] That is, the composition of ethylene-α-olefin copolymer is usually obtained as follows: about 200 mg of the copolymer is uniformly dissolved in 1 ml (milliliter) of hexachlorobutadiene in a Φ10 mm sample tube, and the obtained sample is measured under the measurement conditions of measurement temperature 120°C, measurement frequency 25.05 MHz, spectrum width 1500 Hz, pulse repetition time 4.2 seconds, and pulse width 6 μsec. 13 C-NMR spectrum.

[0039] The polymer containing ethylene as a main component used in the present invention is characterized by satisfying the following requirements (a), (b), (c), (d), and (e).

[0040] Regarding (a)

[0041] Density measured according to JIS K 6922 is 900-925 kg / m 3 .

[0042] Among them, the most suitable is 902~920kg / m 3 , more suitable for 903 ~ 915kg / m 3 , further suitable for 904 ~ 913kg / m 3 .

[0043] When the content exceeds this range and becomes higher, the rigidity tends to be too high and the strength tends to be reduced. On the other hand, when the content becomes lower, the heat resistance tends to be reduced.

[0044] Regarding (b)

[0045] The melt flow rate (MFR) measured according to JIS K 6921 (temperature 190°C, load 21.18 N) is 10 to 25 g / 10 minutes, preferably 10 to 20 g / 10 minutes, and more preferably 10 to 15 g / 10 minutes.

[0046] When the MFR exceeds this range and becomes higher, the tensile strength tends to decrease, and when it becomes lower, the high-speed moldability tends to decrease.

[0047] Regarding (c)

[0048] Volume resistivity (2mm thick sheet) is 1.0×10 16 Ω·cm or more.

[0049] The preferred lower limit is 3.0×10 16 Ω·cm or more. The lower limit is more preferably 5.0×10 16 Ω·cm or more. More preferably, the lower limit is 8.0×10 16 Ω·cm or more. In addition, the upper limit is not particularly limited in terms of performance, but because it is a polymer with ethylene as the main component, it is actually 1.0×10 19 Ω·cm or less.

[0050] When the volume resistivity increases, the insulation properties of the wire improve, while when it decreases, the insulation properties decrease. It is known that the volume resistivity of a material generally increases when it does not contain a conductor such as metal. Therefore, it can be inferred that even when polymerization is carried out using a catalyst containing a metal element, the volume resistivity of an ethylene-based polymer with trace amounts of the catalyst remaining will vary depending on the type of metal in the catalyst.

[0051] Regarding (d)

[0052] The shear viscosity measured using a capillary rheometer at a shear rate of 12.2 (1 / s) is greater than 300 (Pa·s) and less than 8000 (Pa·s), and the shear viscosity at a shear rate of 2432 (1 / s) is greater than 30 (Pa·s) and less than 220 (Pa·s).

[0053] In addition, regarding this range, the preferred range is: the shear viscosity at a shear rate of 12.2 (1 / s) is greater than 400 (Pa·s) and less than 5000 (Pa·s), and the shear viscosity at a shear rate of 2432 (1 / s) is greater than 40 (Pa·s) and less than 200 (Pa·s).

[0054] In addition, regarding this range, a more preferred range is: the shear viscosity at a shear rate of 12.2 (1 / s) is greater than 500 (Pa·s) and less than 4000 (Pa·s), and the shear viscosity at a shear rate of 2432 (1 / s) is greater than 50 (Pa·s) and less than 180 (Pa·s).

[0055] In addition, regarding this range, a further preferred range is: the shear viscosity at a shear rate of 12.2 (1 / s) is greater than 500 (Pa·s) and less than 4000 (Pa·s), and the shear viscosity at a shear rate of 2432 (1 / s) is greater than 50 (Pa·s) and less than 120 (Pa·s).

[0056] In addition, regarding this range, the more preferred range is: the shear viscosity at a shear rate of 12.2 (1 / s) is greater than 500 (Pa·s) and less than 2000 (Pa·s), and the shear viscosity at a shear rate of 2432 (1 / s) is greater than 60 (Pa·s) and less than 160 (Pa·s).

[0057] In addition, regarding this range, the particularly preferred range is: the shear viscosity at a shear rate of 12.2 (1 / s) is greater than 500 (Pa·s) and less than 2000 (Pa·s), and the shear viscosity at a shear rate of 2432 (1 / s) is greater than 60 (Pa·s) and less than 100 (Pa·s).

[0058] It should be noted that if the surface has significant unevenness, such as when the diameter of the resin strand flowing out of the capillary rheometer varies by 0.5 mm or more depending on the location, the measured values ​​tend to vary greatly. Therefore, it is preferred to use data measured on a resin strand with a smooth surface.

[0059] Generally, when the viscosity increases at low shear rates, shear stress is easily applied during melt kneading in an extruder, which promotes the exchange of materials such as inorganic flame retardants and fillers, improving dispersion. In materials with poor filler-resin dispersion, localized concentrations of filler may occur.

[0060] In the product, the portion where the filler concentration is higher than the average filler concentration has insufficient resin, so the tensile elongation and tensile strength are reduced, resulting in a portion that is quickly destroyed (weak portion).

[0061] When coating layer of the present invention contains filler, because its dispersibility is good, the result can improve the tensile strength of the coating layer as article formed.When the viscosity under high shear rate is lower, the coarse tendency on the surface of coating layer is suppressed when the molding of coating layer, and as a result, can improve molding speed under the state of not becoming surface roughness.Therefore, only by the adjustment of MFR, be difficult to realize the intensity that depends on the melt mixing of filler etc. and prevent surface roughness of coating layer when improving and high speed molding.

[0062] In the present invention, by selecting a specific range based on the viscosity curve, surface roughness of the coating layer during high-speed molding can be suppressed, molding can be performed at a relatively low resin pressure, and processability can be improved.

[0063] About (e)

[0064] The 50% crack initiation time (F) in the environmental stress crack resistance (ESCR test, 3 mm thick pressed sheet, test temperature 65°C) according to ASTM D1693 was 50 ) is 10 hours or more. More preferably, it is 30 hours or more. Even more preferably, it is 100 hours or more. Even more preferably, it is 200 hours or more. In addition, based on the relationship between actual measurement time, the upper limit is usually 1500 hours, and there are cases of about 1000 hours.

[0065] 50% crack initiation time (F 50 ) tends to decrease long-term durability. A larger value indicates improved durability of the coating layer obtained from the ethylene-α-olefin copolymer. Because the present invention utilizes an insulating material with excellent durability, the insulating material used in the present invention is particularly suitable for flame-retardant, environmentally friendly wire applications containing an inorganic flame retardant.

[0066] Environmental stress cracking resistance (ESCR test) F 50 The value can be adjusted by the molecular weight, density, and compounding amount of the high molecular weight polymer of the ethylene-α-olefin copolymer. By increasing the molecular weight of the high molecular weight polymer, increasing its ratio, or reducing its density, F can be increased. 50 It can be further considered that the environmental stress cracking resistance of polymers with long chain branches, such as high-pressure LDPE with high melt tension and easy processing, is 50 The value is smaller than that of linear polymer. And in order to increase F 50Reducing the long-chain branching in ethylene-α-olefin copolymers is also an option. When used as wire materials, if the copolymer is blended with other polymers primarily composed of ethylene, adjustments to the formulation, such as reducing the amount of the polymer with long-chain branching, may be considered.

[0067] Method for producing polymer containing ethylene as main component

[0068] Polymers containing ethylene as a primary component can be produced by using a conventionally known catalyst system and adjusting polymerization conditions to form a polymer that meets the aforementioned requirements (a) to (e). For example, the density can be adjusted by varying the proportion of the copolymer components in the polymer. Density can be increased by reducing the proportion of the copolymer components. Furthermore, the MFR can be adjusted by adjusting the average molecular weight of the polymer. As the average molecular weight increases, the MFR decreases.

[0069] As defined in (d), in order to adjust the range of shear viscosity for a certain shear rate, there are methods for obtaining the polymer defined in (d) by, for example, forming a composition comprising two polymers having different average molecular weights, or by multi-stage polymerization such as two-stage polymerization in a polymerization method utilizing an existing catalyst system, or by mixing polymers having different average molecular weights. By performing such appropriate molecular weight distribution control, a step is performed to obtain a polymer having the desired viscosity characteristics.

[0070] Method for producing polymer containing ethylene as main component

[0071] Methods for producing polymers containing ethylene as a main component, particularly ethylene-α-olefin copolymers, include methods using conventionally known catalyst systems, for example, single-site catalysts such as metallocene catalysts, and multistage polymerization such as two-stage polymerization.

[0072] Method for producing ethylene-α-olefin copolymer

[0073] The ethylene-α-olefin copolymer having the above-mentioned physical properties can be produced as follows: as component (i) of the transition metal compound of the polymerization catalyst, 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 containing a ligand having a cyclopentadienyl skeleton is used, and ethylene and an α-olefin having 3 to 20 carbon atoms are supplied to the polymerization system, thereby appropriately producing the copolymer.

[0074] In the production of ethylene-α-olefin copolymers, component (ii) (organoaluminum oxy-compound), carrier (iii), and optionally component (iv) (organoaluminum compound) are usually used together with the above-mentioned component (i).

[0075] Each component is described below.

[0076] Component (ii) organoaluminum oxy-compound

[0077] The organoaluminum oxy-compound may be a conventionally known benzene-soluble organoaluminum oxy-compound or a benzene-insoluble organoaluminum oxy-compound disclosed in Japanese Patent Application Laid-Open No. 2-276807. The organoaluminum oxy-compound may be used alone or in combination of two or more. Specific examples include methylaluminoxane.

[0078] Carrier (iii)

[0079] The carrier (iii) used is an inorganic or organic compound, and is preferably a granular or microparticle solid having a particle size of 10 to 300 μm, preferably 20 to 200 μm. Among these, the inorganic carrier is preferably a porous oxide, specifically SiO2, Al2O3, MgO, ZrO2, TiO2, Sb2O3, CaO, ZnO, BaO, ThO2, or mixtures thereof, such as SiO2-MgO, SiO2-Al2O3, SiO2-TiO2, SiO2-V2O5, SiO2-Cr2O3, SiO2-TiO2-MgO, etc. Among these, porous oxides containing at least one component selected from SiO2 and Al2O3 as a main component are preferred.

[0080] Although the shape of the carrier (iii) varies depending on its type and preparation method, it is preferred that the carrier used has a specific surface area of ​​50 to 1000 m 2 / g, preferably 100 to 700 m 2 / g, and the pore volume is preferably 0.3 to 2.5 cm 3 The support (iii) may be fired at a temperature of 100 to 1000°C, preferably 150 to 700°C, as required.

[0081] Other usable carriers (iii) include granular or particulate solids of organic compounds having a particle size of 10 to 300 μm. Examples of these organic compounds include (co)polymers containing as main components α-olefins having 2 to 14 carbon atoms, such as ethylene, propylene, 1-butene, and 4-methyl-1-pentene, or polymers or copolymers containing as main components vinylcyclohexane or styrene.

[0082] Component (iv) organoaluminum compound

[0083] As the organoaluminum compound of component (iv) added as needed, compounds represented by the following general formula (I) can be exemplified.

[0084] R 1(n) AlX (3-m) ········(I)

[0085] (Where 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.

[0086] As R 1 , for example, an alkyl group, a cycloalkyl group or an aryl group, specifically a methyl group, an ethyl group, a n-propyl group, an isopropyl group, an isobutyl group, a pentyl group, a hexyl group, an octyl group, a cyclopentyl group, a cyclohexyl group, a phenyl group, a tolyl group, etc.

[0087] Specific examples of such organoaluminum compounds include the following compounds.

[0088] Trialkylaluminums such as trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, trioctylaluminum, and tri(2-ethylhexyl)aluminum; alkenylaluminums such as isoprenylaluminum; and dialkylaluminum halides such as dimethylaluminum chloride, diethylaluminum chloride, diisopropylaluminum chloride, diisobutylaluminum chloride and dimethylaluminum bromide.

[0089] Furthermore, as the organoaluminum compound, a compound represented by the following general formula (II) can also be used.

[0090] R 1 (n) AlY (3-n) ·····(II)

[0091] (Where R 1 Represents the same as R in the above general formula (I) 1 Same hydrocarbon group. Y represents -OR 2 Base, -OSi(R 3 )3 base, -OAl(R 4 )2-base, -N(R 5 )2-base, -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 is methyl, ethyl, isopropyl, isobutyl, cyclohexyl, phenyl, etc., R 5 is a hydrogen atom, methyl, ethyl, isopropyl, phenyl, trimethylsilyl, etc., R 6 and R 7 is methyl, ethyl, etc.)

[0092] Specifically, the following compounds can be used as such an organoaluminum compound.

[0093] R1 (n) Al(OR 2 ) (3－n) The compounds shown, such as dimethylaluminum methoxide, diethylaluminum ethoxide, diisobutylaluminum methoxide, etc.;

[0094] R 1 (n) Al(OSi(R 3 )3) (3－n) The compounds shown, such as Et2Al(OSiMe3), (iso-Bu)2Al(OSiMe3), (iso-Bu)2Al(OSiEt3), etc.;

[0095] R 1 (n) Al(OAl(R 4 )2) (3－n) The compounds shown, such as Et2AlOAlEt2, (iso-Bu)2AlOAl(iso-Bu)2, etc.;

[0096] R 1 (n) Al(N(R 5 )2) (3－n) The compounds shown, such as Me2AlNEt2, Et2AlNHMe, Me2AlNHEt, Et2AlN(SiMe3)2, (iso-Bu)2AlN(SiMe3)2, etc.;

[0097] R 1 (n) Al(Si(R 6 )3) (3－n) The compounds shown, such as (iso-Bu)2AlSiMe3, etc.;

[0098] R 1 (n) Al(N(R 7 )Al(R 8 )2) (3－n) The compounds shown, for example, Et2AlN(Me)AlEt2, (iso-Bu)2AlN(Et)Al(iso-Bu)2, etc.

[0099] Among the organoaluminum compounds represented by the above general formula (I) and general formula (II), the general formula (R 1 )3Al、(R 1 ) n Al(OR 2 ) (3－n) 、(R 1 ) n Al(OAl(R4 )2) (3－n) The compound shown, particularly preferably R 1 The compound wherein n=2 is an isoalkyl group.

[0100] Catalyst preparation method

[0101] The polymerization catalyst can be prepared, for example, by contacting the above-mentioned components (i), (ii), and (iii) the support, and optionally (iv). The order of contacting the components can be arbitrarily selected, but preferably, the support (iii) and (ii) are mixed and contacted, followed by the above-mentioned component (i), and then, if necessary, by the component (iv).

[0102] The polymerization catalyst may be a prepolymerized catalyst obtained by prepolymerizing an olefin such as ethylene in the presence of the component (i), the component (ii), the carrier (iii), and, if necessary, the component (iv).

[0103] The prepolymerization can be carried out by introducing an olefin such as ethylene into an inert hydrocarbon solvent in the presence of the component (i), the component (ii), the carrier (iii), and, if necessary, the component (iv).

[0104] The prepolymerization catalyst can be prepared, for example, by the following method. That is, the support (iii) is made into a suspension in an inactive hydrocarbon. Then, an organoaluminum oxide compound (component (ii)) is added to the suspension and allowed to react for a set time. Then, the supernatant is removed and the resulting solid component is resuspended in an inactive hydrocarbon. A transition metal compound (component (i)) is added to the system, allowed to react for a set time, and the supernatant is removed to obtain a solid catalyst component. Then, the solid catalyst component obtained above is added to an inactive hydrocarbon containing an organoaluminum compound (component (iv)), and olefins such as ethylene are introduced therein to obtain a prepolymerization catalyst.

[0105] The prepolymerization can be carried out in either a batch or continuous manner and can be carried out under reduced pressure, normal pressure, or increased pressure. During the prepolymerization, it is desirable to produce a prepolymer having an intrinsic viscosity [η] of at least 0.2 to 7 (dl / g), preferably 0.5 to 5 (dl / g), as measured in decalin at 135°C in the presence of hydrogen.

[0106] Aggregation Method

[0107] The ethylene-α-olefin copolymer used in the present invention can be obtained by copolymerizing ethylene and an α-olefin having 3 to 20 carbon atoms in the presence of the above-mentioned polymerization catalyst or prepolymerization catalyst.

[0108] The copolymerization of ethylene and α-olefins is carried out in the gas phase or in the liquid phase in the form of a slurry. In slurry polymerization, an inert hydrocarbon or the olefin itself can be used as the solvent.

[0109] Specific examples of the inactive hydrocarbon solvent used in the 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. Among these inactive hydrocarbon media, aliphatic hydrocarbons, alicyclic hydrocarbons, and petroleum fractions are preferred.

[0110] When the polymerization is carried out by a slurry polymerization method or a gas phase polymerization method, it is desirable that the concentration of the transition metal atoms in the polymerization reaction system of the olefin polymerization catalyst or the prepolymerized catalyst is generally 10 ﹣8 ~10 ﹣3 Gram atoms / liter, preferably 10 ﹣7 ~10 ﹣3 The amount used is gram atoms / liter.

[0111] Furthermore, an organoaluminum oxy-compound similar to component (ii) and / or an organoaluminum compound similar to component (iv) may be added during polymerization. In this case, the atomic ratio (Al / M) of the aluminum atoms (Al) derived from the organoaluminum oxy-compound and the organoaluminum compound to the transition metal atoms (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.

[0112] When the slurry polymerization method is carried out, the polymerization temperature is usually in the range of -50 to 100°C, preferably 0 to 90°C. When the gas phase polymerization method is carried out, the polymerization temperature is usually in the range of 0 to 120°C, preferably 20 to 100°C.

[0113] The polymerization pressure is usually atmospheric pressure ~ 100kg / cm 2 , preferably 2 to 50 kg / cm 2 Under the pressurized conditions, the polymerization can be carried out in any of the following ways: intermittent, semi-continuous or continuous, and can also be carried out in a multi-stage manner such as two-stage polymerization.

[0114] Furthermore, it is desirable to use one or more polymerizers to divide the copolymerization into two or more stages with different reaction conditions.

[0115] 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, inorganic or organic fillers, etc., as needed.

[0116] Insulation materials

[0117] The insulating material of the present invention comprises a polymer primarily composed of ethylene. It may be composed solely of a polymer primarily composed of ethylene, or it may be a composition further comprising another olefin-based polymer. As described above, since the polymer primarily composed of ethylene satisfies requirements (a) to (e), it exhibits excellent extrusion properties, resulting in an excellent insulating material. This allows for the provision of an electric wire having a coating layer with excellent electrical resistance, mechanical strength, and a good appearance.

[0118] The insulating material of the present invention may contain other polymers such as high-pressure low-density polyethylene, linear low-density polyethylene, high-density polyethylene, polypropylene, EVA, and modified polyethylene as needed, within a range that does not impair the performance of the wire. For example, when containing high-pressure low-density polyethylene, the proportion thereof is 3 to 40% by weight, more preferably 10 to 35% by weight.

[0119] Furthermore, when providing an electric wire that places importance on strength, a crosslinking agent may be blended into the polymer containing ethylene as the main component of the insulating material. As the crosslinking agent, peroxides, silane compounds, etc. are preferably used.

[0120] Examples of the peroxide include dicumyl peroxide, tert-butyl cumyl peroxide, 1,3-bis(tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)-hexyne-3, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 1-(2-tert-butylperoxyisopropyl)-4-isopropylbenzene, and 1-(2-tert-butylperoxyisopropyl)-3-isopropylbenzene. These peroxides are blended 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.

[0121] Examples of silane compounds include vinyltrimethoxysilane and vinyltriethoxysilane. These silane compounds can be used in combination with the aforementioned peroxides, with 0.3 to 5 parts, preferably 0.5 to 3 parts, by weight per 100 parts by weight of the insulating material. Furthermore, when using a silane compound, a crosslinking catalyst can be used in combination, such as di-n-butyltin dilaurate and di-n-octyltin dilaurate.

[0122] When a peroxide alone is added as a crosslinking agent, the crosslinking reaction can be initiated by heat, while when a silane compound is added, the crosslinking reaction can be initiated by water. Furthermore, the ethylene-α-olefin copolymer of the present invention can also be crosslinked by irradiation with ionizing radiation such as electron beams. Furthermore, the crosslinking method, type and amount of the crosslinking agent, and crosslinking conditions can be selected so that the final degree of crosslinking reaches 25% or greater, preferably 40% or greater.

[0123] Furthermore, within the scope that does not impair the purpose of the present invention, the insulating material may also contain additives such as antioxidants, weathering stabilizers, light stabilizers, heat stabilizers, antistatic agents, lubricants, pigments, dyes, nucleating agents, plasticizers, hydrochloric acid absorbers, and flame retardants, as needed. The flame retardants that can be used are not limited, and organic flame retardants containing halogen resins can also be used. For example, inorganic flame retardants such as magnesium hydroxide and aluminum hydroxide, which are often used in products known as flame-retardant and environmentally friendly wires, can be used. The content of fillers such as inorganic flame retardants in the insulating material is preferably at least 30% by weight and no more than 80% by weight.

[0124] When the insulating material is a polymer with ethylene as the main component, when a cross-linking agent is added to the insulating material and a cross-linking treatment is performed, the insulating material layer coated on the conductor or conductor shielding layer is converted into a cross-linked structure, which will improve heat resistance and thermal cycling properties.

[0125] Method for manufacturing electric wires

[0126] The electric wire of the present invention is manufactured by extruding and coating the conductor or conductor shield with the insulating material comprising the aforementioned polymer primarily composed of ethylene. First, the insulating material is supplied to an extrusion coating molding machine, melted, and fed to the front of the extruder. Meanwhile, the electric wire is supplied to a right-angle feed die located at the top of the extruder, where the molten insulating material is extruded and continuously coated around the wire. The insulating material layer can be the outermost layer of the wire, or the outer surface of the insulating material layer can be further coated with other resins or other materials.

[0127] When the insulating material primarily comprises an ethylene-based polymer, it is not only used in an uncrosslinked state but may also be used as a coating layer made of a crosslinked insulating material. Crosslinking may be achieved using electron beams or ultraviolet rays, but it is preferred to use an insulating material that contains a crosslinking agent. In this case, the crosslinking treatment is performed after the coating layer is formed under the above-mentioned extrusion conditions.

[0128] When a peroxide is used as a crosslinking agent, the insulating material is crosslinked by heating to a temperature above the decomposition temperature of the peroxide. However, one method is to first mix the peroxide with a composition of a polymer mainly composed of ethylene and other olefin-based polymers in an extruder to preliminarily form a composite, and then coat the composite with the composite and heat it to produce an electric wire having a crosslinked insulating material.

[0129] Furthermore, when a silane compound is used as a crosslinking agent, the insulating material can also be crosslinked by the action of water by immersing the overmolded article in warm water or exposing it to air. In this case, a polymer primarily composed of ethylene or a composition of a polymer primarily composed of ethylene and other olefinic polymers is first introduced into the hopper of an extruder. Separately, a silane compound, a peroxide, and a crosslinking catalyst are continuously injected between the hopper and the extruder or into the barrel of the extruder. This produces an insulating material graft-copolymerized with the silane compound in the extruder, while simultaneously coating the wire. The overmolded article is then immersed in warm water or exposed to air to produce an electric wire coated with the crosslinked insulating material.

[0130] Alternatively, as another method, a silane compound and a peroxide are first blended into an ethylene-α-olefin copolymer or a composition of an ethylene-α-olefin copolymer and another ethylene-based polymer to produce a grafted product. A crosslinking catalyst masterbatch is then added to the grafted product and introduced into an extruder to coat the wire. The coated product is then immersed in warm water or exposed to air to crosslink the insulating material, thereby producing a coated wire.

[0131] The electric wire of the present invention comprises an insulating material containing a polymer having ethylene as a main component and having excellent extrusion processability, and can provide an electric wire having a coating layer having excellent electrical resistance characteristics, mechanical strength, and good appearance.

[0132] Example

[0133] Next, the present invention will be described with reference to Examples, but the present invention is not limited to these Examples.

[0134] Physical properties, capillary rheology curves, and evaluations were performed using the following methods.

[0135] Density (kg / m 3 )

[0136] The measurement was performed in accordance with JIS K 6922.

[0137] Melt flow rate (MFR) (g / 10min, 190℃)

[0138] The measurement was performed at a temperature of 190° C. and a load of 21.18 N in accordance with JIS K 6921.

[0139] Shear viscosity (Pa·s)

[0140] The measurement was performed using a capillary rheometer under the following conditions.

[0141] Determination method

[0142] Melt viscosity (flow curve) determination.

[0143] Device: Capillary rheometer "Capillograph 1D"

[0144] (Toyo Seiki Co., Ltd.)

[0145] Capillary: L = 30 mm, D = 1 mm, inflow angle = 180°

[0146] Extrusion speed: 1, 2, 5, 10, 20, 50, 100, 200 mm / min

[0147] Measurement temperature: 190°C

[0148] Filler mixing performance during compounding

[0149] If the shear viscosity at a shear rate of 12.2 (1 / s) measured using a capillary rheometer is low, sufficient shear stress is transmitted to the resin, causing sufficient positional movement of the resin and fillers such as inorganic flame retardants within the extruder, then the "filler mixing performance during compounding" is judged as "○".

[0150] On the other hand, if the shear viscosity is too high, the shear stress transmitted to the resin is insufficient, and thus sufficient positional movement of the resin and filler in the extruder cannot be caused, and the result is judged as "X".

[0151] Surface roughness during high-speed molding

[0152] If the shear viscosity at a shear rate of 2432 (1 / s) measured using a capillary rheometer is sufficiently high to maintain the smoothness of the wire surface, the "surface roughness during high-speed molding" is rated "○." On the other hand, if the shear viscosity is low and the wire surface loses its smoothness, the rating is "×."

[0153] Note that if the resin strands flowing out of the capillary rheometer have significant surface irregularities such as diameter variations of 0.5 mm or more depending on the position, the measured values ​​will vary greatly. Therefore, it is preferable to make determinations based on data with a smooth surface.

[0154] Environmental stress crack resistance (ESCR) (Hr.)

[0155] The measurement was carried out according to ASTM D 1693, using a 3 mm thick pressed sheet.

[0156] Long-term durability

[0157] If the ESCR durability time measured according to the method of ASTM D1693 is sufficiently high and the weather resistance is excellent, the "long-term durability" is judged as "○".

[0158] Volume resistivity (Ω·cm)

[0159] The measurement was performed according to ASTM D257: 2007. A 2 mm thick pressed sheet was used.

[0160] Electrical insulation properties

[0161] If the value measured according to the method of ASTM D257:2007 is sufficiently high and the insulation is ensured, the "electrical insulation performance" is judged as "○", and if it is not ensured, the "electrical insulation performance" is judged as "×".

[0162] (Example 1)

[0163] An ethylene-α-olefin copolymer (Evolue SP15151, manufactured by Primen Polymer Co., Ltd.) was fed into a 100 mm Φ single-screw extruder. Separately, a 16 mm Φ conductor was fed into a right-angle feed die. The conductor was continuously coated to form a 2.5 mm thick coating layer. The extruder barrel and die temperatures were set at 200°C. The physical properties of the resulting wire coating layer were measured, and the results are shown in Table 1.

[0164] (Comparative Examples 1 to 5)

[0165] In each comparative example, the same procedure as in Example 1 was carried out except that the following polyethylene resin was used. The results are shown in Table 1.

[0166] Comparative Example 1: ELITE 5220G manufactured by Dow Chemical Company,

[0167] Density: 915(kg / m 3 ), MFR: 3.5 (g / 10 minutes, 190°C)

[0168] Comparative Example 2: COHERE S100 manufactured by SABIC,

[0169] Density: 915(kg / m 3 ), MFR: 1 (g / 10 minutes, 190°C)

[0170] Comparative Example 3: SUMIKATHENE G701 manufactured by Sumitomo Chemical,

[0171] Density: 919 (kg / m 3 ), MFR: 6.9 (g / 10 minutes, 190°C)

[0172] Comparative Example 4: Asahi Kasei SUNTEC-LD M2270,

[0173] Density: 923 (kg / m 3), MFR: 7 (g / 10 minutes, 190°C)

[0174] Comparative Example 5: NEO-ZEX 25500J manufactured by Prime Polymer Co., Ltd.

[0175] Density: 926 (kg / m 3 ), MFR: 50 (g / 10min, 190°C)

[0176] [Table 1]

[0177]

[0178] Industrial applicability

[0179] The electric wire of the present invention has a coating layer that is excellent in extrusion processability, and also has excellent electrical resistance characteristics and mechanical strength, and can be suitably used as an electric wire in a wide variety of fields.

Claims

1. An electric wire, characterized in that: The conductor or the conductor shielding layer is covered with an insulating material containing a polymer with ethylene as a main component, and the polymer with ethylene as a main component satisfies the following requirements (a) to (e): (a) Density measured according to JIS K 6922 is 900 to 925 kg / m 3 , (b) a melt flow rate (MFR) measured in accordance with JIS K 6921 (temperature 190°C, load 21.18 N) of 10 to 25 g / 10 minutes, (c) The volume resistivity (2 mm thick pressed sheet) measured according to ASTM D257:2007 is 1.0×10 16 Ω·cm or more, (d) the shear viscosity at a shear rate of 12.2 (1 / s) measured using a capillary rheometer is 300 (Pa·s) to 8000 (Pa·s), and the shear viscosity at a shear rate of 2432 (1 / s) is 30 (Pa·s) to 220 (Pa·s), Determination method: Melt viscosity (flow curve) determination: Device: Capillary Rheometer "CAPILOGRAPH 1D" (Toyo Seiki Co., Ltd.), Capillary: L = 30 mm, D = 1 mm, inflow angle = 180°, Extrusion speed: 1, 2, 5, 10, 20, 50, 100, 200 mm / min, Measurement temperature: 190°C, (e) 50% crack initiation time (F) in environmental stress crack resistance (ESCR test, 3 mm thick pressed sheet, test temperature 65°C) measured according to ASTM D1693 50 ) is more than 10 hours.

2. The electric wire according to claim 1, wherein: The volume resistivity (2 mm thick pressed sheet) of the polymer (c) with ethylene as the main component measured according to ASTM D257:2007 is 1.0×10 16 Ω·cm or above 1.0×10 19 Ω·cm or less.

3. The electric wire according to claim 1, wherein: The polymer containing ethylene as a main component of the insulating material is a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms.

4. The electric wire according to claim 1, wherein: The insulating material is compounded with a flame retardant.

5. The electric wire according to claim 1, wherein: The insulating material is compounded with a cross-linking agent.

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