JP5191081B2 - Electric wire, polyethylene resin material for power cable and composition thereof, and electric wire and power cable using them - Google Patents

Description

  The present invention relates to an electric wire in which the generation of organic volatile components is suppressed and less environmental pollution, a polyethylene resin material for power cables, a polyethylene resin composition thereof, an electric wire using the same, and an electric power cable. More specifically, the present invention relates to a polyethylene resin material obtained by removing volatile organic compounds caused by low molecular weight components and additives remaining in the polyethylene resin, a polyethylene resin composition thereof, and an electric wire and a power cable using them. is there.

  Low-density polyethylene has excellent moldability and electrical characteristics while being inexpensive, and is widely used as an insulating layer and a covering layer in electric wire applications such as electric wires and power cables. Among electric wire applications, in the case of electric wires and power cables used in clean rooms of so-called IT-related factories such as semiconductor manufacturing plants and liquid crystal manufacturing plants, volatile organic substances from electric wires are products such as silicon wafers and glass substrates. Organic pollution due to deposition on top has been pointed out. In order to solve this problem, for example, in Patent Document 1 (Japanese Patent Laid-Open No. 2001-52533) and Patent Document 2 (Japanese Patent Laid-Open No. 2002-203435), a wiring cable used in a clean room is bonded to one side. A method by wrapping and covering with a polymer organic film which does not allow organic gas to pass through is applied. However, although this method is excellent in suppressing organic gas generated from the wiring cable, it takes time and effort to coat the wiring cable with the film, and the workability during construction is poor. Moreover, when the said film peels with time, we are anxious about volatilization of the volatile organic compound from an adhesive agent. Moreover, in patent document 3 (Unexamined-Japanese-Patent No. 2002-190217), about the non-halogen flame-retardant electric wire and cable, outgas (organic) by using the composition which mix | blended the antioxidant and plasticizer which do not contain an organic volatile component. A method for reducing volatile components) is shown. However, since this method limits only highly volatile antioxidants and plasticizers, the suppression of organic volatile components is insufficient, and in particular, the amount of volatile components required for low-density polyethylene that does not use plasticizers is suppressed. Levels and types are different.

JP 2001-52533 A JP 2002-203435 A JP 2002-190217 A

  In the polyethylene for electric wires and power cables, the present invention finds that the main factors of organic volatile components are not only antioxidants and plasticizers, but particularly low molecular weight derived from polyethylene and highly volatile hydrocarbon compounds, It has been found that by reducing specific hydrocarbon compounds, organic volatile components from electric wires and power cables are suppressed, and can be sufficiently used in a clean room or the like.

[1] The polyethylene resin material for electric wires and power cables of the present invention is manufactured by a high-pressure radical polymerization method (a) density 0.91 g / cm ^{3 to} 0.94 g / cm ³ , (b) melt mass flow rate (MFR) ) 0.1 g / 10 min to 5 g / 10 min, (c) 100-60 mass% of low density polyethylene resin having a ratio (Mw / Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) of 8 or less and it will remove the volatile organic compound of a polyethylene resin material consisting of 0-40% by weight other polyolefin resin, and (b) the content of more than 12 hydrocarbon compounds carbon 50ppm or less, and (ii) a molecular weight A polyethylene resin material for electric wires and power cables, characterized in that the content of an antioxidant having a melting point of 500 or less and a melting point of 80 ° C. or less satisfies a property of 10 ppm or less.

[2] The polyethylene resin composition for electric wires and power cables of the present invention is manufactured by a high-pressure radical polymerization method (a) density 0.91 g / cm ^{3 to} 0.94 g / cm ³ , (b) melt mass flow rate ( MFR) 0.1 g / 10 min to 5 g / 10 min, (c) Low density polyethylene resin having a ratio (Mw / Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) of 8 or less 100 to 60 mass Volatile organic compounds of polyethylene resin material consisting of 0% and 40% by mass of other polyolefin resin , and further blended with an unsaturated alkoxysilane compound, an organic peroxide, and optionally a silanol condensation catalyst, and ( A) The content of hydrocarbon compounds having 12 or less carbon atoms is 50 ppm, and (b) the content of antioxidants having a molecular weight of 500 or less and a melting point of 80 ° C. or less is 10 ppm. It is a polyethylene resin composition for electric wires and power cables, comprising a polyethylene resin composition satisfying the following properties.

[3] The water-crosslinkable electric wire and power cable polyethylene resin composition of the present invention is produced by a high-pressure radical polymerization method (a) density 0.91 g / cm ^{3 to} 0.94 g / cm ³ , (b) melt Low density polyethylene resin 100 having a mass flow rate (MFR) of 0.1 g / 10 min to 5 g / 10 min, (c) a ratio (Mw / Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) of 8 or less Volatile organic compound of polyethylene resin material consisting of ~ 60% by mass and other polyolefin resin 0 ~ 40% by mass is removed, and further, unsaturated alkoxysilane compound, organic peroxide and optionally silanol condensation catalyst are blended. It is produced by raising the polyethylene resin composition to a temperature higher than the decomposition temperature of the organic peroxide, and (a) the content of the hydrocarbon compound having 12 or less carbon atoms is 50 ppm or less. , And (ii) a molecular weight of 500 or less, a water-crosslinkable cable, the polyethylene resin composition for electric power cables, wherein the content of the melting point of 80 ° C. The following antioxidants satisfies the following properties 10 ppm.

[4] The polyethylene resin material for electric wires and power cables according to [1] above, wherein the volatile organic compound of the polyethylene resin material is removed by any one of the following methods (1) to (4).
(1) a method in which the low-density polyethylene during the production of have your degassing step to volatilize the hydrocarbon compound by raising the treatment temperature,
(2) In the pelletizing step during production, a method of drawing the hydrocarbon compound by a negative pressure from a vent port provided in the extruder,
(3) Reduce hydrocarbon compounds by stirring the pellets after production in a warm water of 60 ° C. or higher, or in a warm water and in an inert gas in a low oxygen concentration atmosphere having a dissolved oxygen concentration of 0.5 mg / L or less. Method,
(4) This is a method of volatilizing the hydrocarbon compound in the air at 60 ° C. or higher or in an inert gas.
[5] The polyethylene resin composition for electric wires and power cables according to the above [2] or [3], wherein a volatile organic compound of the polyethylene resin material is removed by any one of the following methods (1) to (4).
(1) a method in which the low-density polyethylene during the production of Te degassing step odor, to volatilize the hydrocarbon compound by raising the treatment temperature,
(2) In the pelletizing step during production, a method of drawing the hydrocarbon compound by a negative pressure from a vent port provided in the extruder,
(3) Reduce hydrocarbon compounds by stirring the pellets after production in a warm water of 60 ° C. or higher, or in a warm water and in an inert gas in a low oxygen concentration atmosphere having a dissolved oxygen concentration of 0.5 mg / L or less. Method,
(4) This is a method of volatilizing the hydrocarbon compound in the air at 60 ° C. or higher or in an inert gas.
[6] The electric wire and power cable of the present invention are characterized by using the polyethylene resin material or the polyethylene resin composition according to any one of [1] to [5] as an insulating layer and / or a covering layer. Electric wires and power cables.

[ 7 ] The electric wire and power cable of the present invention have the polyethylene resin material or polyethylene resin composition according to any one of [1] to [ 5 ] as an insulating layer, and the polyethylene resin material according to [1] is the most preferred. It is an electric wire or a power cable characterized by being an outer layer.

  In the present invention, in a low density polyethylene produced by a high pressure radical polymerization method, its molecular weight distribution (Mw / Mn), carbon number and content of volatile hydrocarbons, and an antioxidant having a specific molecular weight and melting point. By controlling the content within a specific range, we provide electric wires and power cables. By using these wires and power cables in clean rooms of IT-related factories, it is possible to reduce contamination of IT-related products by organic compounds. To do.

[Embodiment of the Invention]
The polyethylene resin material of the present invention is produced by a high-pressure radical polymerization method (a) density 0.91 g / cm ^{3 to} 0.94 g / cm ³ , (b) melt mass flow rate (MFR) 0.1 g / 10 min. 5 g / 10 min, (c) 100 to 60% by mass of low density polyethylene resin having a ratio (Mw / Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) of 8 or less, and other polyolefin resins 0 to 40 And (b) a content of a hydrocarbon compound having 12 or less carbon atoms, and / or (b) a content of an antioxidant having a molecular weight of 500 or less and a melting point of 80 ° C. or less of 10 ppm or less. It is characterized by satisfying. Extrudability due to the broad molecular weight distribution compared to low density polyethylene produced by medium and low pressure methods using Ziegler catalysts, chromium catalysts and metallocene catalysts. It is possible to provide electric wires and power cables that are excellent in electrical characteristics such as tree resistance and dielectric breakdown resistance because they have excellent inorganic properties such as catalyst and porous inorganic oxide used for supporting the catalyst. is there.

[Low density polyethylene resin]
The (a) density (JIS K6922-1 (1997), JIS K6922-2 (1997), measured by the density gradient tube method) of the low density polyethylene resin of the present invention is 0.91 g / cm ^{3 to} 0.94 g / cm. ^3, preferably ^{0.915 / cm 3 ~0.940g / cm 3} , more preferably ^{0.920g / cm 3 ~0.940g / cm 3} , particularly preferably 0.925g ^/ cm 3 ~0.94g ^/ cm ³ .
If the density is less than 0.91 g / cm ³ , mechanical strength, heat resistance and the like may be reduced. Moreover, when the density exceeds 0.94 g / cm ³ , the stress crack resistance may be deteriorated.

  (B) Melt mass flow rate (MFR: JIS K6922-2 (1997), condition D (measured at 190 ° C., 21.18 N)) of the low density polyethylene resin is 0.1 to 5 g / 10 min, preferably 0.8. 1 to 3 g / 10 minutes. When the MFR is less than 0.1 g / 10 minutes, the extrudability during the molding process is deteriorated, and when it exceeds 5 g / 10 minutes, the mechanical strength may be lowered or the melt tension during the molding process may be lowered.

(C) Molecular weight distribution (ratio of weight average molecular weight (Mw) to number average molecular weight (Mn): Mw / Mn) of the low density polyethylene resin is 8 or less, preferably 4.0 to 7.0, more preferably It is in the range of 5.0 to 6.5. When Mw / Mn exceeds 8, the molecular weight distribution becomes wide, so that the melt elasticity at the time of molding process becomes too large, and the surface of the electric wire or power cable may be roughened. Also, the semiconductive layer, insulating layer, sheath layer If there is rough skin at the interface, etc., the tree resistance and the like may be deteriorated. Furthermore, since the molecular weight distribution is broadened, and the amount of low molecular weight components increases, especially hydrocarbon compounds having 12 or less carbon atoms, which will be described later, increase, the amount of organic volatile components from electric wires and power cables may increase.
In order to obtain low-density polyethylene with Mw / Mn of 8 or less, the tubular method is used in the high-pressure radical polymerization method because some polyethylene found in the autoclave method stays in the polymerization tank for a long time. It is preferable because it does not produce a high molecular weight component, and is produced using a known method at a polymerization temperature of 200 to 400 ° C. and a polymerization pressure of 150 to 350 MPa.

For Mw and Mn of low density polyethylene, a 1 mg / mL solution of a low density polyethylene sample was prepared using o-dichlorobenzene (containing 0.5 mg / mL BHT), and it took about 1 hour at 140 ° C. And dissolved by gel permeation chromatography (GPC) method under the following conditions. Conversion from the retention volume to the molecular weight is performed using a calibration curve prepared in advance with standard polystyrene.
Equipment: GPC (ALC / GPC 150C) manufactured by WATERS
Detector: MIRAN 1A IR detector manufactured by FOXBORO (measurement wavelength: 3.42 μm)
Column: AD806M / S (3 pieces) manufactured by Showa Denko KK
Mobile phase solvent: o-dichlorobenzene Measurement temperature: 140 ° C
Flow rate: 1.0 ml / min Injection volume: 0.2 ml
Standard polystyrene: manufactured by Tosoh Corporation, F380, F288, F128, F80, F40, F20, F10, F4, F1, A5000, A2500, A1000
Calibration curve: A calibration curve is prepared by injecting 0.2 mL of a solution of standard polystyrene in o-dichlorobenzene (containing 0.5 mg / mL BHT) to 0.5 mg / mL. The calibration curve uses a cubic equation obtained by approximation by the least square method.
Conversion of molecular weight: The following numerical value is used for the viscosity equation [η] = K × M ^α used for conversion to molecular weight.
PS: K = 1.38 × 10 ⁻⁴ α = 0.7
PE: K = 3.92 × 10 ⁻⁴ α = 0.733

  The high-pressure radical polymerization method can use a known method for performing radical polymerization of ethylene at a pressure of 100 MPa to 500 MPa and a temperature of 100 ° C. to 400 ° C. As described above, a low density polyethylene resin having a molecular weight distribution of 8 or less is produced. In order to do so, the production method by the tubular method is preferable among the high-pressure radical polymerization methods because there is no generation of a high molecular weight component that is generated when a part of polyethylene found in the autoclave method stays in the polymerization tank for a long time. . In particular, it is desirable to produce in a range of polymerization temperature of 200 to 400 ° C. and polymerization pressure of about 150 to 350 MPa.

In the polyethylene resin material of the present invention, (i) the content of the hydrocarbon compound having 12 or less carbon atoms is 50 ppm or less, preferably 30 ppm or less, more preferably the content of hydrocarbon compounds having 12 or less carbon atoms is 20 ppm or less. In addition, the content of the hydrocarbon compound having 30 or less carbon atoms is desirably 200 ppm or less.
If the content of hydrocarbon compounds with 12 or less carbon atoms exceeds 50 ppm, the amount of organic volatile components from electric wires and power cables increases, so there is a risk that semiconductor-related products will be organically contaminated when used in a clean room. The content of the hydrocarbon compound is 50 ppm or less, preferably 30 ppm or less, more preferably 20 ppm or less, and further preferably 10 ppm or less and 1 ppm or less. However, the low molecular weight component of polyethylene having a molecular weight distribution is reduced. In the present invention, the amount of hydrocarbon compounds that volatilize at fairly high temperatures is quantified by gas chromatography, so it is mainly used for electric wires and power cables used at room temperature. Is the effect of the present invention when the content of the hydrocarbon compound by the measurement method of the present invention is 50 ppm or less. It is.

  As a method of obtaining a polyethylene resin material having a hydrocarbon compound content of 12 or less carbon atoms of 50 ppm or less, in the degassing treatment step during the production of the low density polyethylene, the pressure difference with the polymerization pressure is increased, or the treatment temperature The method of volatilizing the hydrocarbon compound by raising the method, the method of pulling the hydrocarbon compound by negative pressure from the vent port provided in the extruder in the pelletizing step at the time of production, the pellet after the production, 60 ° C. or more, A method of reducing hydrocarbon compounds by stirring or the like, preferably in warm water at 80 ° C. or higher, more preferably in a low oxygen concentration atmosphere with dissolved oxygen of 0.5 mg / L or lower in an inert gas, and similarly pellets at 60 ° C. As mentioned above, the method etc. which volatilize a hydrocarbon compound in the air of 80 degreeC or more preferably still more preferably in an inert gas etc. are mentioned.

The content of the hydrocarbon compound having 12 or less carbon atoms in the polyethylene resin material is such that 50 ± 5 mg of a sample of the polyethylene resin material is filled in a heat-extracting tube filled with 30 mg of quartz wool at both ends, and then in the sample under the following conditions. Volatile hydrocarbons are extracted by heating and collected and measured by a dynamic head space-gas chromatography / mass spectrum (DHS-GC / MS) method. The qualitative and quantitative determination of the carbon number of the hydrocarbon compound is performed using a calibration curve prepared in advance by n-eicosane.
(Heating expulsion, collection conditions)
Equipment: TDS manufactured by GERSTEL
Heating condition: 150 ° C. (40 ° C. to 60 ° C./min heating rate), 10 minutes Carrier gas: helium, flow rate 50 mL / min Collection temperature: −150 ° C.
(GC / MS measurement conditions)
Apparatus: GC HP6890 manufactured by Agilent
Mass Sensitive Detector 5973N (EI) manufactured by Agilent
Column: DB-5 (length 60 m, 0.25 mm · ID, 1.0 μm · Df)
Measurement temperature: heating of collected components 325 ° C., 10 minutes
Column temperature 300 ° C (temperature increase rate from 50 ° C to 10 ° C / min)
Carrier gas: helium, flow rate 1.4 mL / min Measurement mode: MS (Scan-EI Positive)
Measurement mass range: m / z 14 to 500

(Create a calibration curve)
The qualitative carbon number of the hydrocarbon compound is that n-heptane is used as a solvent to prepare an approximately 1000 μg / mL solution of aliphatic saturated linear hydrocarbons having 2 to 2 carbon atoms up to 10 to 30 carbon atoms, and 1 μL of the solution is heated and expelled. After collecting by heating at 300 ° C. for 5 minutes in a tube, it was determined from the retention time obtained by GC / MS measurement under the same conditions as the polyethylene sample.

The content of the hydrocarbon compound is determined by preparing a 1000 μg / mL n-eicosane solution using n-hexane as a solvent, collecting 1 μL of the solution by heating at 300 ° C. for 5 minutes in a heat extraction tube, and then collecting a polyethylene sample. As a standard amount, the peak area obtained by GC / MS measurement under the same conditions as above was quantified from the peak area observed in the GC retention time range of the aliphatic saturated linear hydrocarbon having 10 to 30 carbon atoms.
Retention time range for hydrocarbon compounds having 12 or less carbon atoms: 15.2 minutes or less Retention time range for hydrocarbon compounds having 30 or less carbon atoms: 46.5 minutes or less Fixed mass range: m / z 57
Volatile component amount: S = (A _PE −A _B ) / (K _C20 × w _PE ) (ppm)
K _C20 = (A _C20 -A _B ) / w _C20
Here, all the peak areas obtained in the retention time of A _PE hydrocarbon compounds generated from the sample, A _B is the peak area of the blank, K _C20 in peak area per weight of n- eicosane, standard n- The difference between the peak area of Eicosan (A _C20 ) and the peak area of the blank (A _B ) divided by the weight of injected n-eicosane (w _C20 , μg), and w _PE is the weight of the sample measured (g) It is.

In the polyethylene resin material of the present invention, (b) the content of an antioxidant having a molecular weight of 500 or less and a melting point of 80 ° C. or less is 10 ppm or less, preferably 5 ppm or less, more preferably 1 ppm or less. If the content of antioxidants with a molecular weight of 500 or less and a melting point of 80 ° C. or less exceeds 10 ppm, the amount of organic volatile components from electric wires and power cables increases, so when used in a clean room, semiconductor-related products are organic. There is a risk of contamination.
Further, in order to reduce the content of the hydrocarbon compound having 12 or less carbon atoms in the polyethylene resin material of the present invention to 50 ppm or less, the pellet as described above is heated to 60 ° C. or higher, preferably 80 ° C. or higher, or in the air. When using a method such as heating, there is a risk of thermal degradation if no antioxidant is added. Therefore, it is preferable that an antioxidant having a molecular weight exceeding 500 and a melting point exceeding 80 ° C. is added even in a small amount. .

  As specific antioxidants, hindered phenol antioxidants, phosphorus antioxidants, sulfur antioxidants, and the like are preferable. For example, 2,4,6-tri-t-butylphenol, 2,6- Di-t-butyl-4-hydroxymethylphenol, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-6-t-butylphenol), 4, 4′-methylenebis (2,6-di-t-butylphenol), 2,2′-dihydroxy-3,3′-di (α-methylcyclohexyl) -5,5′-dimethyldiphenylmethane, 2,2′-ethylidene -Bis (4,6-di-t-butylphenol), 2,2'-butylidene-bis (4-methyl-6-t-butylphenol), 4,4'-butylidenebis (3- Til-6-tert-butylphenol), 4,4′-thiobis (3-methyl-6-tert-butylphenol), bis (3,5-di-tert-butyl-4-hydroxybenzyl) sulfide, 4,4 ′ -Di-thiobis (2,6-di-t-butylphenol), 4,4'-tri-thiobis (2,6-di-t-butylphenol), N, N'-bis [3- (3,5- Di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine, tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, pentaerythrityl-tetrakis- [3- (3,5-di -T-butyl-4-hydroxyphenyl) propionate], n-octadecyl-β- (4′-hydroxy-3 ′, 5′-di-t-butylphenyl) propionate, N, N′-he Samethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamide), 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) Benzene, tris (3,5-di-tert-butyl-4-hydroxybenzyl) -isocyanurate, 1,3,5-tris (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 3,9-bis [2- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) -propionyloxy] -1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane, bis (2,4-di-t-butylphenyl) pentaerythritol difo Phyto, tris (2,4-di-t-butylphenyl) phosphite, 2,2'-methylenebis (4,6-di-t-butylphenyl) octyl phosphite, distearyl-pentaerythritol diphosphite, dilauryl -3,3'-thiodipropionic acid ester, dimyristyl-3,3'-thiodipropionic acid ester, distearyl-3,3'-thiodipropionic acid ester, lauryl stearyl-3,3'-thiodipropionic acid Acid ester, pentaerythritol tetra (β-lauryl-thiopropionate) ester, and the like, and one or more selected from these are 0.001 per 100 parts by weight of the low-density polyethylene resin material of the present invention. Parts by weight or more, preferably 0.001-1 parts by weight, more preferably 0.01-0. 5 parts by weight, still more preferably be contained 0.02-0.3 parts by weight.

[Other polyolefin resins]
Examples of other polyolefin resins that can be used in the present invention include α-olefins having 3 to 10 carbon atoms (for example, propylene, 1-butene, etc.), vinyl esters in addition to ethylene homopolymers in the high-pressure radical polymerization method. (For example, vinyl acetate), α, β-unsaturated carboxylic acid or derivatives thereof (for example, acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, methacrylic acid) Propyl, isopropyl acrylate, isopropyl methacrylate, acrylate-n-butyl, methacrylate-n-butyl, cyclohexyl acrylate, cyclohexyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, acrylic acid Guri Dimethyl, glycidyl methacrylate, etc.), acid anhydrides (eg, maleic anhydride, etc.), vinyl silanes (eg, vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltriethoxysilane, etc.), butadiene, divinylbenzene, pentadiene, etc. and ethylene Two or more random, block, or graft copolymers, and mixtures thereof can be used.

In addition, the low density polyethylene resin of the present invention includes other polyolefins in the low density polyethylene resin according to the purpose in order to improve physical properties such as heat resistance, surface appearance, and stress crack resistance. It can mix | blend suitably within. Other polyolefins include high density polyethylene with a density of 0.92 to 0.97 g / cm ³ and linear low density polyethylene (ethylene / α-olefin copolymer), metallocene catalysts produced by a medium or low pressure method. And low density polyethylene (ethylene / α-olefin copolymer) having a density of 0.88 to 0.92 g / cm ³ , polypropylene and the like. The blending amount of these other polyolefins is 40% by mass or less with respect to 60% by mass or more of the low density polyethylene resin, preferably 2 to 30% by mass with respect to 98 to 70% by mass of the low density polyethylene resin, more preferably low density. It is preferable to blend in the range of 5 to 20% by mass with respect to 95 to 80% by mass of the polyethylene resin.

  When the polyethylene resin material for electric wires and power cables of the present invention is used as an insulating layer and / or coating layer for electric wires, it can be used as a low-density polyethylene resin or as a crosslinked product. Specific examples of the crosslinking method include an electron beam crosslinking method, an organic peroxide crosslinking method, and a water crosslinking method. Among these, the water crosslinking method is capable of uniform crosslinking and post-crosslinking, and the equipment cost. Is most preferable because it is inexpensive.

[Water-crosslinkable polyethylene resin composition]
The polyethylene resin composition for water-crosslinkable electric wires and power cables of the present invention is a water-crosslinking obtained by blending an unsaturated alkoxysilane compound, an organic peroxide, and optionally a silanol condensation catalyst into a polyethylene resin material for electric wires and power cables. It is a polyethylene resin composition for conductive wires and power cables.
Moreover, the aspect of the polyethylene resin composition for other water-crosslinkable electric wires and electric power cables comprises blending an unsaturated alkoxysilane compound, an organic peroxide, and, if desired, a silanol condensation catalyst to the polyethylene resin material for electric wires and electric power cables. A water-crosslinkable electric wire and a polyethylene resin composition for electric power cables produced by raising the polyethylene composition for electric power cables and electric power cables to the decomposition temperature of the organic peroxide or higher.
In these compositions as well, it is important to satisfy the properties (a) and / or (b) in the polyethylene resin material.

[Silane crosslinking method]
As the water crosslinking method, an unsaturated alkoxysilane compound and an organic peroxide are extruded together with the polyethylene at a temperature equal to or higher than the decomposition temperature of the organic peroxide to obtain an unsaturated alkoxysilane-grafted polyethylene composition. A method for obtaining a cable product by appropriately mixing a silanol condensation catalyst and a polyethylene composition containing a silanol condensation catalyst which is mixed with the polyethylene and then extruded and kneaded at the time of coating molding of an electric wire, an electric power wire or an electric power cable ( 2-step Sioplasm method), unsaturated alkoxysilane compound, organic peroxide, silanol condensation catalyst, and a composition in which the polyethylene is mixed at the same time, then at a temperature equal to or higher than the decomposition temperature of the organic peroxide, There is a method of obtaining a cable product by covering and molding a power cable (one-step Monosil method)
In the water crosslinking method, electric wires and power cables obtained by coating and molding a polyethylene composition mixed with an unsaturated alkoxysilane compound, an organic peroxide, a silanol condensation catalyst and an antioxidant, It is characterized in that it is cross-linked over time with water in water or in water vapor, but it is possible to crosslink in hot water of 60 ° C. or higher, preferably 80 ° C. or higher, more preferably 90 ° C. or higher, or water vapor. It is preferable as a method for simultaneously reducing volatile organic compounds from the power cable.
Moreover, the water-crosslinking method is not particularly limited as long as it is produced by using the above-mentioned water-crosslinkable electric wire and polyethylene composition for power cables and raising the temperature to the decomposition temperature of the organic peroxide or higher. For example, an unsaturated alkoxysilane compound, an organic peroxide, and the polyethylene are mixed in advance and then charged into an extruder, and then a mixture of the silanol condensation catalyst and the polyethylene is charged with a side feeder and molded with the same extruder. After mixing the method, unsaturated alkoxysilane compound, organic peroxide, and polyethylene, the mixture is put into an extruder to obtain an unsaturated alkoxysilane-grafted polyethylene composition, and then the composition is combined with a silanol catalyst and the polyethylene. A method of melt kneading and molding using a second extruder together with a mixture of polyethylene, and after introducing the polyethylene into the extruder, A method in which a mixture of a Japanese alkoxysilane compound, an organic peroxide, and a silanol condensation catalyst or each of them is fed by a side feeder and melt kneaded and molded by the same extruder, unsaturated alkoxysilane compound, organic peroxide, silanol condensation In order to disperse the catalyst, a known water crosslinking method such as a method of using the polyethylene in the form of a powder in advance by a pulverizer or the like can be used.
Moreover, in the case of water bridge | crosslinking, the heat aging property and shaping | molding workability of the said electric wire and electric power cable can be improved by mixing well-known additives, such as antioxidant and an anti-scratch agent.

[Unsaturated alkoxysilane compound]
Examples of the unsaturated alkoxysilane compound used in the present invention include the following: γ-methacryloyloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropyl-tris- (2- Methoxyethoxy) silane, vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, allyltriethoxysilane, allylmethyldiethoxysilane, diallyldimethoxysilane, allylphenyldiethoxysilane, methoxyvinyldiphenylsilane , Dodecenyl dipropoxy silane, didecenyl dimethoxy silane, didodecenyl methoxy silane, cyclohexenyl trimethoxy silane, hexenyl hexoxy dimethoxy silane, Ru-tri-n-butoxysilane, hexenyl-tri-n-butoxysilane, vinyl-tris (n-butoxy) silane, vinyl-tris (n-pentoxy) silane, vinyl-tris (n-hexoxy) silane, vinyl- Tris (n-heptoxy) silane, vinyl-tris (n-octoxy) silane, vinyl-tris (n-dodecyloxo) silane, vinyl-bis (n-butoxy) methylsilane, vinyl-bis (n-pentoxy) methylsilane, vinyl -Bis (n-hexoxy) methylsilane, vinyl- (n-butoxy) dimethylsilane, vinyl- (n-pentoxy) dimethylsilane, allyl dipentoxysilane, butenyl didecoxysilane, decenyl didecoxysilane, Decenyltrioctoxysilane, heptenyltriheptoxysilane, Rutripropoxysilane, divinyldiethoxysilane, diallyl-di-n-butoxysilane, pentenyltripropoxysilane, allyl-di-n-butoxysilane, secondary butenyltriethoxysilane, β-methacryloxyethyl-tris (n- Butoxy) silane, γ-methacryloxypropyl-tris (n-dodecyl) silane. The unsaturated alkoxysilane is added in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 3 parts by weight, based on 100 parts by weight of the polyethylene.

[Organic peroxide]
As the organic peroxide used in the present invention, free radical sites can be generated in the polyolefin resin under graft reaction conditions, and the half-life is shorter than 6 minutes, preferably shorter than 1 minute at the reaction temperature. Arbitrary compounds having the following can be used, and typical examples include dicumyl peroxide, di-tert-butyl peroxide, benzoyl peroxide, 2,5-di (peroxybenzoate) hexyne-3 and the like. The organic peroxide is blended in an amount of 0.01 to 0.75 part by weight, preferably 0.02 to 0.3 part by weight, based on 100 parts by weight of the polyethylene.

[Silanol condensation catalyst]
As the silanol condensation catalyst used in the present invention, it is used as a catalyst for promoting dehydration condensation between silanols of silicone, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioleate, stannous acetate, naphthenic acid Lead, cobalt naphthenate, zinc caprylate, iron 2-ethylhexanoate, titanate, tetrabutyl titanate, tetranonyl titanate, bis (acetylacetonitrile) di-isopropyltitanium-ethylamine, hexylamine, dibutylamine , Pyridine and the like. The compounding amount of the silanol condensation catalyst is about 0.001 to 10 parts by weight, preferably 0.05 to 5 parts by weight with respect to 100 parts by weight of the polyethylene.

  The composition of the present invention includes an antioxidant, a slip agent, a neutralizing agent, a light-resistant agent, an ultraviolet absorber, an anti-scratch agent, a copper damage inhibitor, and an antistatic agent that are commonly used for polyethylene depending on the application. An agent, a coloring pigment, a filler, a metal hydrate, a flame retardant, and the like can be appropriately mixed.

[Electric wires, power cables]
(1) The electric wire and electric power cable of the present invention are an electric wire, electric power electric wire, and electric power cable characterized by using the above polyethylene for an insulating layer and / or a covering layer.
(2) Other electric wires and electric power cables are characterized in that the water-crosslinking electric wires and the polyethylene composition for electric power cables are used for the insulating layer and / or the coating layer and are water-crosslinked. It is.
(3) Further, the third electric wire and the power cable may be formed by using the polyethylene or water-bridged electric wire, the polyethylene composition for electric power cable as an insulating layer, and an electric wire or electric power cable having the polyethylene as the outermost layer (hereinafter referred to as “electric cable”). Simply called a cable).
The cable of the present invention is not particularly limited as long as it is a cable using the above-described polyethylene of the present invention, and may be a combination of the cables of (1) and (2), and is semiconductive through the insulating layer. A layer or the like may be provided. For example, a cable in which the insulating layer is a crosslinked polyethylene and the covering layer is an uncrosslinked body, and conversely, a cable in which the insulating layer is an uncrosslinked polyethylene and the covering layer is a crosslinked body.
Further, the cable of the present invention has a cable structure in which, for example, ordinary polyethylene is used for the insulating layer, and the polyethylene resin material is used only for the covering layer, thereby preventing the organic volatile components from evaporating from the inside of the cable. It can also be used as a body.

Hereinafter, the embodiment will be described in more detail.
In addition, the property of the low density polyethylene resin used by the Example and the comparative example is as follows.
LDPE1 : A phenolic antioxidant (penta) produced by a tubular high-pressure radical polymerization method and having a density of 0.929 g / cm ³ , MFR 0.5 g / 10 min, Mw / Mn 4.3, molecular weight 1177, melting point 110 ° C. or higher. Low density polyethylene in which 0.1 part by weight of erythrityl-tetrakis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]) is added to 100 parts by weight of polyethylene.
LDPE2 : Low density polyethylene produced by a tubular high-pressure radical polymerization method with a density of 0.918 g / cm ³ , MFR 1.9 g / 10 min, Mw / Mn 6.8, and no antioxidant added.
LDPE3 : Low density polyethylene produced by an autoclave type high-pressure radical polymerization method, density 0.918 g / cm ³ , MFR 2.0 g / 10 min, Mw / Mn 9.8, no antioxidant added.
HDPE1 : A phenolic antioxidant (pentaerythrityl-tetrakis-) produced by a low pressure polymerization method using a Ziegler catalyst and having a density of 0.955 g / cm ³ , MFR 0.6 g / 10 min, a molecular weight of 1177, and a melting point of 110 ° C. or higher. [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]) and a phosphorus antioxidant having a molecular weight of 647 and a melting point of 180 ° C. (Tris (2,4-di-t-butylphenyl) High density polyethylene in which 0.05 part by weight of phosphite) is added to 100 parts by weight of polyethylene.
Moreover, shaping | molding of the covered electric wire using polyethylene was implemented on condition of the following.
Molding machine: Nippon Steel Works, wire coating molding machine Extruder: 50 mm diameter, single screw extruder, screw L / D22
Dice: Die outlet outer diameter 1.2mm
Molding temperature: 220 ° C
Screw rotation speed: 16rpm
Take-off speed: 50 m / min Cooling: Water bath temperature 30 ° C
Electric wire shape: copper core wire diameter 0.9mm, covered wire diameter 1.5-1.6mm

LDPE 1 and 10 kg were heat-treated in a gear oven at 75 ° C. for 24 hours in the air to obtain a low density polyethylene resin material for electric wires and power cables having a content of hydrocarbon compounds having 12 or less carbon atoms of 22 ppm.
The resulting low-density polyethylene resin material was used for wire covering molding to obtain a covered electric wire of about 50 m. The surface appearance of the obtained covered electric wire was good. Only the polyethylene coating layer was cut out from the obtained covered electric wire, and the content of a hydrocarbon compound having 12 or less carbon atoms was measured. The results are shown in Table 1.

LDPE 1 and 10.8 kg were mixed with HDPE 1 and 1.2 kg with a V blender for 2 minutes, then melt kneaded at 230 ° C. and 50 rpm using a single screw extruder having a diameter of 50 mm, cooled and pelletized, and a density of 0. 10 kg of low density polyethylene (LDPE4) of 932 g / cm ³ , MFR 0.5 g / 10 min, Mw / Mn 4.5 was obtained.
Using the obtained low density polyethylene, heat treatment was performed in the same manner as in Example 1 to obtain a low density polyethylene resin material for electric wires and electric cables having a content of hydrocarbon compounds having 12 or less carbon atoms of 16 ppm.
Using the obtained low-density polyethylene resin material, a covered electric wire was obtained in the same manner as in Example 1. The surface appearance of the obtained covered electric wire was good. Only the polyethylene coating layer was cut out from the obtained covered electric wire, and the content of a hydrocarbon compound having 12 or less carbon atoms was measured. The results are shown in Table 1.

In Example 1, the heat treatment time of LDPE 1 was set to 16 hours to obtain a low-density polyethylene resin material for electric wires and electric cables with a content of hydrocarbon compounds having 12 or less carbon atoms of 48 ppm.
Using the obtained low-density polyethylene resin material, a covered electric wire was obtained in the same manner as in Example 1. The surface appearance of the obtained covered electric wire was good. Only the polyethylene coating layer was cut out from the obtained covered electric wire, and the content of a hydrocarbon compound having 12 or less carbon atoms was measured. The results are shown in Table 1.
[Comparative Example 1]

In Example 1, the LDPE 1 was not heat-treated, and wire covering molding was performed using a low-density polyethylene resin material having a hydrocarbon compound content of 12 or less carbon atoms of 339 ppm. Obtained. The surface appearance of the obtained covered electric wire was good. Only the polyethylene coating layer was cut out from the obtained covered electric wire, and the content of a hydrocarbon compound having 12 or less carbon atoms was measured. The results are shown in Table 1.
[Comparative Example 2]

In Example 2, the LDPE 4 was not heat-treated, and wire covering molding was performed using a low-density polyethylene resin material having a hydrocarbon compound content of 12 or less carbon atoms of 295 ppm. Obtained. The surface appearance of the obtained covered electric wire was good. Only the polyethylene coating layer was cut out from the obtained covered electric wire, and the content of a hydrocarbon compound having 12 or less carbon atoms was measured. The results are shown in Table 1.
[Comparative Example 3]

In Example 2, LDPE 1, 9 kg, LDPE 1 powder 1.8 kg, HDPE 1, 1.2 kg, molecular weight 221 and melting point 70 ° C. phenol antioxidant (2,6-di-t-butyl) previously pulverized by a turbo pulverizer After mixing 2.4 g of (-4-methylphenol) with a super mixer for 2 minutes, the mixture was melt kneaded at 230 ° C. and 50 rpm using a single screw extruder having a diameter of 50 mm, cooled, pelletized, and a density of 0.932 g / cm. ³ , 10 kg of low density polyethylene having MFR 0.5 g / 10 min and Mw / Mn 4.5 was obtained.
Using the obtained low density polyethylene, heat treatment was performed in the same manner as in Example 1 to obtain a low density polyethylene resin material for electric wires and electric power cables having a content of hydrocarbon compounds having 12 or less carbon atoms of 18 ppm.
Using the obtained low-density polyethylene resin material, a covered electric wire was obtained in the same manner as in Example 1. The surface appearance of the obtained covered electric wire was good. Only the polyethylene coating layer was cut out from the obtained covered electric wire, and the content of a hydrocarbon compound having 12 or less carbon atoms was measured. The results are shown in Table 1. Further, a phenolic antioxidant (2,6-di-t-butyl-4-methylphenol) having a molecular weight of 500 or less and a melting point of 80 ° C. or less determined by the same method as that for measuring hydrocarbon compounds having 12 or less carbon atoms. Table 1 shows the measurement results of the content of). The antioxidant is quantified by using a total ion chromatogram instead of a quantitative mass range m / z57 in the method for measuring hydrocarbon compounds, and in the vicinity of a retention time of 20.0 min, which is the peak of the antioxidant determined in advance. Using the recognized peak intensity, it was determined in terms of n-eicosane as in the measurement of the hydrocarbon compound.
[Comparative Example 4]

In Example 1, the LDPE 2 was not heat-treated, and wire covering molding was performed using a low-density polyethylene resin material having a hydrocarbon compound content of 12 or less carbon atoms of 1276 ppm. Obtained. The surface appearance of the obtained covered electric wire was good. Only the polyethylene coating layer was cut out from the obtained covered electric wire, and the content of a hydrocarbon compound having 12 or less carbon atoms was measured. The results are shown in Table 1.
[Comparative Example 5]

  In Example 1, the LDPE 3 was not heat-treated, and wire covering molding was performed using a low-density polyethylene resin material having a hydrocarbon compound content of 12 or less carbon atoms of 1746 ppm. Obtained. The covered electric wire obtained under the same molding conditions as in Example 1 had a change in thickness and the product appearance was not smooth. Only the polyethylene coating layer was cut out from the obtained covered electric wire, and the content of a hydrocarbon compound having 12 or less carbon atoms was measured. The results are shown in Table 1.

[Evaluation results]
In Examples 1 to 3, since the content of the hydrocarbon compound having 12 or less carbon atoms is 50 ppm or less, the volatilization amount of the volatile hydrocarbon compound from the coating layer is low even after the wire coating.
In Comparative Examples 1, 2, and 4, since the content of the hydrocarbon compound having 12 or less carbon atoms exceeds 50 ppm, the volatilization amount of the volatile hydrocarbon compound from the coating layer after the wire coating is large.
In Comparative Example 3, although the content of the hydrocarbon compound having 12 or less carbon atoms is 50 ppm or less, the amount of the antioxidant having a molecular weight of 500 or less and a melting point of 80 ° C. or less exceeds 10 ppm. Antioxidants are detected as volatile components.
In Comparative Example 5, since Mw / Mn was large, the content of the hydrocarbon compound having 12 or less carbon atoms was large, and the surface appearance of the covered electric wire was also bad.

Claims (7)

(A) density of 0.91 g / cm ^{3 to} 0.94 g / cm ³ , which is produced by a high-pressure radical polymerization method,
(B) Melt mass flow rate (MFR) 0.1 g / 10 min to 5 g / 10 min,
(C) Polyethylene comprising 100 to 60% by mass of a low density polyethylene resin having a weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw / Mn) of 8 or less and 0 to 40% by mass of other polyolefin resin. Volatile organic compounds in the resin material are removed, and (a) the content of hydrocarbon compounds having 12 or less carbon atoms is 50 ppm or less, and (b) the inclusion of an antioxidant having a molecular weight of 500 or less and a melting point of 80 ° C. or less. A polyethylene resin material for electric wires and power cables, characterized in that the amount satisfies the properties of 10 ppm or less. (A) density of 0.91 g / cm ^{3 to} 0.94 g / cm ³ , which is produced by a high-pressure radical polymerization method,
(B) Melt mass flow rate (MFR) 0.1 g / 10 min to 5 g / 10 min,
(C) Polyethylene comprising 100 to 60% by mass of a low density polyethylene resin having a weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw / Mn) of 8 or less and 0 to 40% by mass of other polyolefin resin. A volatile organic compound is removed from the resin material, and further, an unsaturated alkoxysilane compound, an organic peroxide, and optionally a silanol condensation catalyst are blended, and (a) the content of the hydrocarbon compound having 12 or less carbon atoms is A polyethylene resin composition for electric wires and power cables, comprising a polyethylene resin composition satisfying the properties of 50 ppm or less and (b) an antioxidant having a molecular weight of 500 or less and a melting point of 80 ° C. or less and 10 ppm or less. . (A) density of 0.91 g / cm ^{3 to} 0.94 g / cm ³ , which is produced by a high-pressure radical polymerization method,
(B) Melt mass flow rate (MFR) 0.1 g / 10 min to 5 g / 10 min,
(C) Polyethylene comprising 100 to 60% by mass of a low density polyethylene resin having a weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw / Mn) of 8 or less and 0 to 40% by mass of other polyolefin resin. Remove the volatile organic compound from the resin material, and further raise the polyethylene resin composition comprising an unsaturated alkoxysilane compound, an organic peroxide, and optionally a silanol condensation catalyst above the decomposition temperature of the organic peroxide. And (b) a content of a hydrocarbon compound having 12 or less carbon atoms is 50 ppm or less, and (b) a content of an antioxidant having a molecular weight of 500 or less and a melting point of 80 ° C. or less is 10 ppm or less. A polyethylene resin composition for water-crosslinkable electric wires and power cables. The polyethylene resin material for electric wires and electric power cables according to claim 1, wherein a volatile organic compound of the polyethylene resin material is removed by any one of the following methods (1) to (4).
(1) a method in which the low-density polyethylene during the production of Te degassing step odor, to volatilize the hydrocarbon compound by raising the treatment temperature,
(2) In the pelletizing step during production, a method of drawing the hydrocarbon compound by a negative pressure from a vent port provided in the extruder,
(3) Reduce hydrocarbon compounds by stirring the pellets after production in a warm water of 60 ° C. or higher, or in a warm water and in an inert gas in a low oxygen concentration atmosphere having a dissolved oxygen concentration of 0.5 mg / L or less. Method,
(4) A method in which a hydrocarbon compound is volatilized in air at 60 ° C. or higher, or in an inert gas, after the manufactured pellets. The polyethylene resin composition for electric wires and power cables according to claim 2 or 3, wherein a volatile organic compound of the polyethylene resin material is removed by any one of the following methods (1) to (4).
(1) a method in which the low-density polyethylene during the production of Te degassing step odor, to volatilize the hydrocarbon compound by raising the treatment temperature,
(2) In the pelletizing step during production, a method of drawing the hydrocarbon compound by a negative pressure from a vent port provided in the extruder,
(3) Reduce hydrocarbon compounds by stirring the pellets after production in a warm water of 60 ° C. or higher, or in a warm water and in an inert gas in a low oxygen concentration atmosphere having a dissolved oxygen concentration of 0.5 mg / L or less. Method,
(4) A method in which a hydrocarbon compound is volatilized in air at 60 ° C. or higher, or in an inert gas, after the manufactured pellets.   An electric wire and a power cable, wherein the polyethylene resin material or the polyethylene resin composition according to any one of claims 1 to 5 is used for an insulating layer and / or a coating layer. An electric wire and a power cable, wherein the polyethylene resin material or the polyethylene resin composition according to any one of claims 1 to 5 is used as an insulating layer, and the polyethylene resin material according to claim 1 is used as an outermost layer.