Polymeric insulating composition and electric wire or cable covered with such composition

FIELD: electrical engineering.

SUBSTANCE: proposed polymeric insulating composition given in description of invention together with description of cables and wires covered with such composition to ensure their excellent performance in service has 60 to 90 mass percent of copolymer A of ethylene and α-olefin produced by copolymerization with aid of concentric catalyst and 40 to 10 mass percent of polyolefin resin B other than copolymer A and includes polyolefin incorporating grafted substituents with dipole moment 4 D or higher. One of alternative compositions uses semiconducting composition as semiconductor layer. In particular cases ethylene and α-olefin copolymer is produced by polymerization with aid of Ziegler-Natta catalyst.

EFFECT: facilitated production.

8 cl, 2 tbl

 

The technical field

The present invention relates to insulating polymer compositions and electric wires and cables with coatings made from such polymer compositions.

The level of technology

Cross-linked polyethylene is widely used as an insulating material for power cables. Such cross-linked polyethylene is prepared by mixing low density polyethylene, obtained at high pressure (hereinafter referred to as LDPE). low-density polyethylene) and having excellent insulating properties, with cross-linking agent (usually an organic peroxide and an antioxidant, and stitching molecular chains LDPE in such a way that it improves the heat resistance. Cross-linked polyethylene is an excellent insulating material in the case of transfer AC (alternative current, AC).

In recent years, actively explore the transmission of DC (direct current, DC)that is very effective for long lines; however, cross-linked polyethylene cable AC is unstable when changing polarity and, thus, is not applicable in practice to provide a DC.

Dielectric breakdown during the change of polarity is due to the fact that the electric field near the electrode is distorted spatial charge accumulated in the insulating material, and the electric field increases is about two times while changing polarity. The problem of dielectric breakdown can be solved by creating traps of space charge in the insulation material, as described in not examined published patent applications in Japan No. 1999-134942 and 1993-198217.

In connection with the latest developments in the field of catalytic methods developed copolymer of ethylene and α-olefin obtained with the use of "single-site" catalyst, i.e. the catalyst with a single center of polymerization on the metal or one of the catalyst (hereinafter referred to sLLDPE). Compared with a copolymer of ethylene and α-olefin, obtained using a conventional Ziegler catalyst-Coloring (Ziegler-Natta) and called forth zLLDPE, it becomes possible to obtain LLDPE with a uniform molecular weight distribution and uniform distribution, because of the reactive section is homogeneous due to the use of one of the catalyst. It is known that highly uniform sLLDPE detects an improved impact resistance, it contains a reduced amount of the low molecular weight component, which reduces the mechanical strength, and it increases the number of bound molecules in a layered structure. Thus, as can be predicted improvement in pulse resistance for electrical shock, it is proposed to apply sLLDPE as electrical insulation (not proseds what I examination published patent application of Japan No. 1999-29616).

It can be expected that the combination of the two above technologies will allow us to get insulating material with improved properties in the case of DC; however, it was found that this material finds extremely poor extraterrest. In other words, the uniformity of the molecular mass distribution of sLLDPE causes some problems: compression (pressure) of the resin is increased if the extrusion is carried out at the same temperature as in the case of LDPE; surface formed by extrusion products has a tendency to the formation of roughness due to the low tension of the melt and the processability is poor because of the low tension of the melt (like sugar syrup).

Made several attempts to improve manufacturability by mixing sLLDPE with other polyolefin resins, however, useful technology that combines the electrical properties for DC and adaptability, not developed.

The invention

As described above, the space charge accumulated in the insulating material while supplying direct current (DC), causes distortion of the electric field in the insulating material and generates a localized part of a strong electric field when the polarity changes from positive to negative; therefore, it may happen dielectric breakdown.

The inventors have done the wheelie-depth studies to solve the aforementioned problems and found the accumulation of space charge is significantly reduced by vaccination during the polymerization of the substituents having a dipole moment of not less than 4 Debye, to a resin composition mainly composed of a copolymer of ethylene and α-olefin obtained by copolymerization using the so-called "single-site" catalyst, i.e. a catalyst with a single center of polymerization on the metal, for brevity referred to as one of the catalyst. The inventors have made the present invention as a result of further studies based on this discovery.

The present invention includes the following positions.

(1) Insulating polymer composition comprising 60-90 wt.% copolymer (A) ethylene and α-olefin obtained by copolymerization using one catalyst, and 40-10 wt.% the polyolefin resin (B), which is the other polyolefin than the copolymer (A) ethylene and α-olefin, and polymer composition comprises a polyolefin to which using the graft copolymerization graft Deputy, having a dipole moment of not less than 4 Debye.

(2) Insulating polymer composition according to item (1), in which the rate of flow of the melt of the copolymer (A) ethylene and α-olefin obtained by copolymerization with ispolzovatwindows catalyst, ranges from 2 to 10.

(3) Insulating polymer composition according to item (1), in which the polyolefin resin (B) represents at least one resin selected from the group consisting of low density polyethylene, obtained at high pressure; a copolymer of ethylene and α-olefin obtained by copolymerization using a catalyst of the Ziegler-Coloring; and a copolymer of ethylene and α-olefin obtained by copolymerization using one catalyst and having at least 2.5 times lower than the rate of flow of the melt than the copolymer (A) ethylene and α-olefin.

(4) Insulating polymer composition according to item (1), in which the rate of flow of the melt of the polyolefin resin (b) is from 0.1 to 10.

(5) Insulating polymer composition according to item (1), in which the Deputy, having a dipole moment of not less than 4 Debye, obtained by graft polymerization of one or more substances selected from the group consisting of naphthalenol acid, nataliago anhydride, maleic acid, maleic anhydride, basis of itaconic acid, crotonic acid and naphthoic acid.

(6) an electric wire or cable, characterized in that the conductor covered with insulating resin composition according to any of the positions(1)-(5).

(7) e is tricocci wire or cable, characterized in that as a semi-conducting layer between the conductor and the insulating layer and between the insulating layer and a protective layer provided semi-conductive polymer composition made of an electrically insulating polymeric composition according to any one of items (1)to(5) by adding ensuring conductivity material, such as coal.

Insulating polymer composition according to items (1)to(5) detects high resistance to DC voltage, pulse voltage and resistance to change polarity. Furthermore, since the insulating polymer composition has excellent extraterrest, it can be advantageously used as an insulating material for covering electric conductors of wires or cables.

When the semiconductor layer using semi-conducting polymer composition consisting, for example, from the commonly used copolymer of ethylene and vinyl acetate (EVA) or a copolymer of ethylene and ethyl acrylate (EEA), each of which is added to ensure the conductivity of the material, then the impurities contained in the semi-conducting polymer composition, migrate into the insulation, resulting in problems such as increased accumulation of space charge in the insulation and reducing the insulating characteristics of isolation the first material. Thus, reduced benefits insulating resin composition of the present invention.

If the semiconductor layer using semi-conducting polymer composition obtained by adding ensuring the conductivity of the material (such as coal) to the insulating resin composition according to items (1)to(5)as described above in item (7), the accumulation of space charge in the insulation material can be reduced due to the composition of the semi-conducting layer.

Accordingly, the electric wire or cable in which the insulation material used insulating polymer composition described in items (1)to(5), and insulating polymer composition described in items (1)to(5), to which is added providing conductivity material (such as coal), used as a semi-conducting layer located between the conductor and the insulation layer and between the insulating layer and protective layer, detects a particularly high resistance to DC voltage, pulse voltage and resistance to change polarity.

Thus, the present invention provides an electric wire or cable with plastic insulation with high performance properties for the transmission of DC.

Polymer whom azizia according to the present invention, having high electrical insulating properties, contains 60 to 90 wt.% copolymer (A) ethylene and α-olefin and 40-10 wt.% another polyolefin resin (B). The above characteristics are satisfactorily achieved at the specified content data components. When the content of the component (A) less than 60 wt.% electrical properties and/or processability is markedly reduced. The alleged reasons described below.

(1) the improvement of electrical properties using the copolymer (A) is that the use of one of the catalyst (in particular, metallocene catalyst) leads to the fact that the molecular mass distribution and the distribution of the composition in the copolymer of ethylene and α-olefin are uniform, and the content of low-molecular-weight component is low and, hence, the share of associated molecules in a layered structure increases, and, accordingly, increase ("reinforced") of the amorphous part.

(2) it is Assumed that a sharp deterioration in electrical properties when the content of the component (A) less than 60 wt.% is called increasing (extension) of the electrically weak amorphous parts, determining electrical properties.

In this description, the flow velocity of the melt (from the English. melt flow rate, MFR) represents the amount, in units of mass (g), pellets of the polyolefin resin to the e extruded in 10 minutes at 190° With under a load of 2.16 kg according to ASTM D1238-65T.

Preferred embodiments of the inventions

Now the present invention will be described in more detail.

[Copolymer of (A) ethylene and α-olefin]

The copolymer (A) ethylene and α-olefin according to the present invention receives the statistical copolymerization of monomers of ethylene and α-olefin in the presence of a catalyst with a single center of polymerization on the metal, for brevity referred to as one of the catalyst. The copolymer (A) ethylene and α-olefin preferably has a MFR of 2 to 10, so it can be used for coating electric wires or cables, as described above.

The monomer α-olefin preferably contains from 3 to 20 carbon atoms. Examples α-olefinic monomers are propylene, 1-butene, 1-penten, 1-hexene, 1-hepten, 1-octene, 1-none, 1-mission 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecane, 1-hexadecene, 1-heptadecene, 1 octadecene, 1-nonadecane, 1 achozen, 3-methyl-1-penten, 3-ethyl-1-penten, 4-methyl-1-penten, 4-methyl-1-hexene, 4,4-dimethyl-1-penten, 4,4-diethyl-1-penten, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 9-methyl-1-mission 11-methyl-1-dodecene and 12-ethyl-1-tetradecene. You can use one of those a-olefin monomers, or you can use two or more in combination.

Among these α-olefinic monomial is s particularly preferred monomers with 4-10 carbon atoms, for example, propylene, 1-butene, 1-penten and 1-octene.

The copolymerization of ethylene and α-olefin can be carried out in a known way using one of the catalyst.

[Polyolefin resin (C)]

Polyolefin resin (C)used with the copolymer (A) ethylene and α-olefin, preferably has an MFR of 0.1 to 10, assuming machinability, such as extraterrest.

This copolymer (B) may represent at least one resin selected from the group consisting of (1) low density polyethylene, obtained at high pressure; (2) a copolymer of ethylene and α-olefin obtained by copolymerization using a catalyst of the Ziegler-Coloring; and (3) a copolymer of ethylene and α-olefin obtained by copolymerization using one catalyst and having at least 2.5 times lower than the rate of flow of the melt than the copolymer of ethylene and α-olefin (A).

The polyethylene (1) low density, obtained at high pressure, can be a polyethylene, which is produced by polymerization of ethylene using a radical polymerization initiator, such as oxygen or an organic peroxide, under conditions of high temperature and high pressure and which has a density in the range from 0.910 g/cm3to less than 0.930 g/cm3according to the industrial standard is the mouth of Japan (JIS) 6748.

A copolymer of ethylene and α-olefin obtained by copolymerization using a catalyst of the Ziegler-Coloring (the above (2)), is obtained by adding α-olefin in the polymerization of ethylene and the introduction of side chains having the specified length relative to the polyethylene, as defined by JIS To 6748. Examples α-olefinic monomers are 1-butene, 1-hexene, 4-methylpentene and 1-octene.

As the polyolefin resin (B), above (3), it is possible to use a copolymer of ethylene and α-olefin obtained by copolymerization using one catalyst, if MFR of such a copolymer is at least 2.5 times smaller than the above-mentioned copolymer (A). In other words, when you mix two of a copolymer of ethylene and α-olefin obtained by copolymerization using one of the catalysts and having different MFR, the resulting polymer composition has electrical properties and workability necessary for the present invention.

Resin (a) and (b) in the present invention can be stitched or unstitched. When the resin sew, decomposed residue of a crosslinking agent before the application is removed by evaporation. The crosslinking can be carried out in a known method using an organic peroxide such as hydrogen peroxide of Dicumyl, α,αbis-(tert-BUTYLPEROXY-p-isoprop the l)benzene or 2,5-dimethyl-2,5-di(tert-BUTYLPEROXY)hexyne-3.

[The Deputy, having a dipole moment of not less than 4 Debye]

Insulating polymer composition of the present invention contains a polyolefin to which a method of graft polymerization of the grafted substituents having a dipole moment of not less than 4 Debye. Through this polar groups are evenly distributed in the polymeric composition, and the spatial charge is captured in these polar groups. The content of the grafted component is preferably in the range from 10 to 10,000 ppm (parts per million) relative to the composition. The content of grafted component exceeding the upper limit of the specified interval, may cause increased amounts of impurities (increased number of particles (unbar number))which do not pass through the sieve during extrusion and degrade the physical properties, i.e. crystallinity, while the content of the grafted component is less than the specified lower limit leads to the loss of trapping charge. As described above, examples of the substituents are one or more residual group selected from the group consisting of the residual groups naphthalenol acid, nataliago anhydride, maleic acid, maleic anhydride, basis of itaconic acid, crotonic acid and naphthoic acid.

[Insulating polymeric composition]

Electroporation the second polymer composition of the present invention can be obtained by mixing the resin (a) and (b), as well as resin (a) And (b)to which is grafted maleic anhydride, for example, using rolls at a temperature of 140°C-180°C. In the process of obtaining, if necessary, in a known manner to add an antioxidant; however, the decrease in properties caused by such addition, in the insulating resin composition of the present invention is not detected.

[Coating on the conductor]

Insulating polymer composition can be applied to the conductors, such as electrical wires or cables, any conventional method of forming a coating by extrusion. Coating by extrusion can be applied directly to the conductors or semi-conducting layers, or protective layers formed on the conductors.

EXAMPLES 1-5 AND EXAMPLES 1-3 TO COMPARE

Polymer materials (a) and (b) and uterine mixture is inoculated by the method of graft polymerization of maleic anhydride, kneaded on rolls at 150°thus, to obtain the compositions listed in table 1 (examples 1-5) and table 2 (examples 1-3 for comparison), respectively, and from the thus obtained compositions are formed into patterns in the form of leaves.

The sample cross-linked polyethylene (XLPE). crosslinked polyethylene) in example 3 for comparison kneaded at 120°C.

Each sample experience as described hereinafter IU is the od. The results are given in tables 1 and 2.

(Electrical properties)

Stability when changing polarity. Stability when changing polarity appreciate the phenomenon of accumulation of the space charge, causing distortion of the electric field when changing polarity. In other words, it is estimated by measuring the increase in voltage due to the accumulation of space charge. The closer the voltage is increased to 1, the better.

The resistance of the DC voltage. The resistance of the DC voltage are using relative values when compared with XLPE at room temperature. Preferably, this value was as high as possible.

Resistance pulse voltage. Resistance pulse voltage are using relative values when compared with XLPE at room temperature. Preferably, this value was as high as possible.

(Manufacturability)

Long-term adaptability. Long manufacturability judged by the number of particles (relative value), captured by the sieve 635 mesh during the test by extrusion without guide head using an extruder with a diameter of 20 mm, it is Preferable that this value was as small as possible.

Technologiczne the . Manufacturability evaluated by compressing the resin and reverse motor torque distribution grid during the test by extrusion without guide head using an extruder with a diameter of 20 mm, the temperature of the extrusion 140° (130°in the case of example 3 for comparison).

Table I
EXAMPLES
12345
Resin (A)
MFR4,04,04,04,04,0
Wt.%7060707070
Resin (B)
Type (1)LDPELDPEsLLDPELDPEzLLDPE
MFR0,21,01,30,20,8
Wt.%3030303030
Type (2) sLLDPE
MFR1,3
Wt.%10
Maleic anhydride mol/g ×10-7101010110
(Electric
properties)
- Resistance
voltage DC1,471,511,451,421,5
- Resistance
pulse voltage1,321,221,361,301,31
- Gain voltage
due to spatial is wow
charge1,111,131,111,241,10
(Manufacturability)
- The number of particles0,090,090,050,080,12
Compression resin135140130135145
Musculoskeletal moment5,86,25,2the 5.76,3

In the above tables 1 and 2 use LDPE, zLLDPE and sLLDPE representing the materials described below.

LDPE: low density polyethylene, obtained at high pressure [W2000 (MFR 1.0) and S (MFR 0,2), produced by Japan Polyolefins Co., Ltd.].

zLLDPE: linear low-density polyethylene obtained by polymerization using a catalyst of the Ziegler-Coloring [FZ103-0 (MFR of 0.8), produced by Sumitomo Chemical Co., Ltd.].

sLLDPE: linear low-density polyethylene obtained by polymerization using a metallocene single center catalyst [FV103 (MFR 1,3) and FV401 (MFR of 4.0), produced by Sumitomo Chemical Co., Ltd.].

Stitched pole the ilen: 100 wt. parts W2000, 2.0 wt. part of peroxide of Dicumyl and 0.2 wt. parts of 4,4'-THIOBIS(2-tert-butyl-5-METHYLPHENOL).

As can be seen from example 3 for comparison in table 2, cross-linked polyethylene not containing copolymer (A) ethylene and α-olefin obtained by copolymerization using one catalyst, has a large voltage gain, i.e. 1,42, due to the accumulation of space charge, which indicates poor resistance to change polarity.

As can be seen from example 1 for comparison, in table 2, when the content of the copolymer (A) ethylene and α-olefin obtained by copolymerization using one catalyst, 50%, and the resin (B) used LDPE, resistance pulse voltage is low, i.e. 0,84.

As can be seen from example 2 for comparison, in table 2, when the content of the copolymer (A) ethylene and α-olefin obtained by copolymerization using one catalyst, 50%, and the resin (B) use linear low density polyethylene obtained by polymerization using the metallocene catalyst, the compression of the resin is high, i.e. 160 that indicates poor manufacturability.

Compared with the compositions of examples for comparison, the compositions of examples 1-5 shown in table 1, find excellent resistance voltage is Yu DC and impulse voltage resistance to increased tension and adaptability.

1. Electrical wire or cable, characterized in that as a semi-conducting layer between the conductor and the insulating layer and between the insulating layer and the outer protective layer, respectively, used semi-conductive polymer composition obtained by adding ensuring the conductivity of the insulating material to a polymer composition containing a polymer composition comprising a first copolymer of ethylene and α-olefin obtained by copolymerization using one catalyst, polyolefin resin constituting the other polyolefin than the first copolymer of ethylene and α-olefin and polyolefin with a graft polymerization Deputy, having a dipole moment of not less than 4 Debye.

2. Electrical wire or cable, characterized in that as a semi-conducting layer between the conductor and the insulating layer and between the insulating layer and the outer protective layer, respectively, used semi-conductive polymer composition obtained by adding ensuring the conductivity of the insulating material to polymeric compositions containing from 60 to 90 wt.% first copolymer of ethylene and α-olefin obtained by copolymerization using one catalyst is, from 40 to 10 wt.% the polyolefin resin constituting the other polyolefin than the first copolymer of ethylene and α-olefin and polyolefin with a graft polymerization Deputy, having a dipole moment of not less than 4 Debye.

3. Electrical wire or cable, characterized in that the conductor a coating of electrically insulating polymeric composition comprising a first copolymer of ethylene and α-olefin obtained by copolymerization using one catalyst, polyolefin resin constituting the other polyolefin than the first copolymer of ethylene and α-olefin and polyolefin with a graft polymerization Deputy, having a dipole moment of not less than 4 Debye, and that as a semi-conducting layer between the conductor and the insulating layer and between the insulating layer and the outer protective layer, respectively, used semi-conductive composition obtained by adding ensuring the conductivity of the material to the specified insulating polymeric composition.

4. Electrical wire or cable, characterized in that the conductor a coating of electrically insulating polymeric composition containing from 60 to 90 wt.% first copolymer of ethylene and α-olefin obtained by copolymerization using one catalyst, from 40 to 10 m is S.% polyolefin resin, representing other polyolefin than the first copolymer of ethylene and α-olefin and polyolefin with a graft polymerization Deputy, having a dipole moment of not less than 4 Debye, and that as a semi-conducting layer between the conductor and the insulating layer and between the insulating layer and the outer protective layer, respectively, used semi-conductive composition obtained by adding ensuring the conductivity of the material to the specified insulating polymeric composition.

5. Electrical wire or cable according to any one of claims 1 to 4, characterized in that the flow velocity of the melt of the first copolymer of ethylene and α-olefin obtained by copolymerization using one catalyst is from 2 to 10.

6. Electrical wire or cable according to any one of claims 1 to 4, characterized in that the polyolefin resin represents at least one resin selected from the group consisting of low density polyethylene, obtained at high pressure, of a copolymer of ethylene and α-olefin obtained by copolymerization using a catalyst of the Ziegler-Coloring, and a copolymer of ethylene and α-olefin obtained by copolymerization using one catalyst and having at least 2.5 times lower than the rate of melt flow than the first FOSS is emer ethylene and α -olefin.

7. Electrical wire or cable according to any one of claims 1 to 4, characterized in that the rate of melt flow polyolefin resin is from 0.1 to 10.

8. Electrical wire or cable according to any one of claims 1 to 4, characterized in that the Deputy, having a dipole moment of not less than 4 Debye, obtained by graft polymerization of one or more substances selected from the group consisting of naphthalenol acid, nataliago anhydride, maleic acid, maleic anhydride, basis of itaconic acid, crotonic acid and naphthoic acid.



 

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