WO2018147707A1 - Power cable provided with insulating layer having improved flexibility - Google Patents

Abstract

The present invention relates to a power cable provided with an insulating layer having improved flexibility. The power cable in one embodiment comprises: one or more conductors; an inner semiconductive layer surrounding the conductor(s); an insulating layer surrounding the inner semiconductive layer; an outer semiconductive layer surrounding the insulating layer; a neutral-wire watertight layer surrounding the outer semiconductive layer; and a covering layer surrounding the neutral-wire watertight layer, wherein the insulating layer comprises reactive polypropylene and a polypropylene block copolymer.

Description

Power cable with improved insulation

The present invention relates to a power cable. More particularly, the present invention relates to a power cable having an insulating layer that can be operated for a long time at high temperature and has improved flexibility.

Generally, crosslinked polyethylene resin (XLPE), which is mainly used as an insulation material of power cables, is a thermosetting resin, and thus, has excellent heat resistance and chemical resistance, and excellent electrical characteristics. Method for preparing a crosslinked polyethylene resin is crosslinking and electron beam crosslinking by chemical reaction using an organic peroxide or silane (US Patent No. 6284178 (2011.09.04)) as a medium (US Patent No. 4426497 (1984.01.17)) In the large cable industry, crosslinking type using organic peroxide is most widely used.

Recently, power cable characteristics that are recyclable and have high transmission capacity are required. In order to satisfy the demand, electric wires including an insulating layer made of uncrosslinked polymer resin that can be operated at a maximum allowable temperature of 110 ° C are required.

On the other hand, crosslinked polyethylene resins are thermoset resins prepared by crosslinking polyethylene, so they cannot be recycled, which is difficult to dispose of, causing environmental pollution. In addition, since the melting point of the crosslinked polyethylene is 90 ℃ to 115 ℃ is difficult to operate at a high temperature of 110 ℃ it is not suitable as a material of the insulating layer of the power cable.

In other words, there is a demand for the use of environmentally friendly non-crosslinked thermoplastic resins, but crosslinked polyethylene, which is mainly used, is not enough to be used for power cable insulation materials due to the lack of heat resistance.

Against this backdrop, there is a prior art for non-crosslinked polyethylene resin in Korean Patent Application Publication No. 10-2010-0106871 (published on Oct. 4, 2010) as an insulation material of power cables, but the low shear thinning of the resin during the actual processing. Due to the poor workability there is a problem that the processing defects occur. In addition, there is a problem that the performance is degraded as an insulating layer of the outdoor cable due to poor tracking resistance.

Therefore, in order to solve this problem, it is necessary to develop a power cable capable of operating at a maximum allowable temperature of 110 ° C at all times, including an insulating layer made of a polymer composite resin having a high melting point and not crosslinking.

One object of the present invention is to provide a power cable having an environment-friendly insulating layer excellent in stability and flexibility at high temperatures.

Another object of the present invention is to provide a power cable having excellent heat resistance, low temperature impact resistance, flexibility, mechanical and electrical characteristics.

Another object of the present invention is to provide a power cable that can be recycled by using a new resin as an insulating layer is environmentally friendly, high melting point can be operated for a long time at high temperature.

One aspect of the present invention relates to a power cable having an insulating layer with improved flexibility. In one embodiment the power cable comprises one or more conductors; An inner semiconducting layer surrounding the conductor; An insulating layer surrounding the inner semiconducting layer; An outer semiconducting layer surrounding the insulating layer; A neutral watertight layer surrounding the outer semiconducting layer; And an outer skin layer surrounding the neutral watertight layer, wherein the insulating layer includes a reactive polypropylene and a polypropylene block copolymer, and the insulating layer includes reactive polypropylene and a polypropylene block nose. About 30 parts by weight to about 80 parts by weight of the reactive polypropylene and about 20 parts by weight to about 70 parts by weight of the polypropylene block copolymer, wherein the insulation layer has a flexural modulus of about 2000 kg / cm ² to about 4000 kg / cm ² to be. The flexural modulus may be measured based on ASTM D790 standard.

In one embodiment, the insulating layer may further include an ionic inorganic material. For example, with respect to 100 parts by weight of the total of the reactive polypropylene and polypropylene block copolymer, 55 parts by weight to 65 parts by weight of reactive polypropylene, about 35 parts by weight to about 45 parts by weight of polypropylene block copolymer, And about 0.04 part by weight or less.

In one embodiment, the reactive polypropylene is a polypropylene copolymer formed by polymerizing at least one olefin comonomer selected from ethylene and an α-olefin other than propylene and a propylene monomer in a reactor, and in a matrix comprising the polypropylene copolymer. Ethylene-propylene rubber can be formed by chemically or physically bonding.

In one embodiment, the polypropylene block copolymer comprises about 65 parts by weight to about 82 parts by weight of propylene homopolymer and about 18 parts by weight to about 35 parts by weight of ethylene-propylene rubber. And, the total weight of the ethylene-propylene rubber may include about 25% to about 50% by weight of ethylene.

In one embodiment, the melting point of the reactive polypropylene may be about 160 ° C. or more, a melt enthalpy of about 20 J / g or more, and a melt index of about 0.5 g / 10 min to about 1.5 g / 10 min.

In one embodiment, the melting point of the reactive polypropylene is about 160 ° C to about 170 ° C, the melt enthalpy is about 20J / g to about 30J / g, and the melt index is about 0.7g / 10min to about 0.9g / 10min. Can be.

In one embodiment, the melting point of the polypropylene block copolymer may be about 160 ° C. or more, a melting enthalpy of about 50 J / g to about 70 J / g, and a melting index of about 2.5 g / 10 min to about 3.5 g / 10 min. .

In one embodiment, the flexural modulus measured according to ASTM D790 standard of the reactive polypropylene is about 500kg / cm ² to about 1500kg / cm ² The flexural modulus measured according to ASTM D790 standard of the polypropylene block copolymer may be about 8500kg / cm ² to about 9500kg / cm ² .

In one embodiment, the flexural modulus measured according to ASTM D790 standard of the reactive polypropylene is about 1000kg / cm ² The flexural modulus measured according to ASTM D790 standard of the polypropylene block copolymer may be about 9000 kg / cm ² .

In one embodiment, the melting point of the insulating layer may be about 160 ℃ to about 170 ℃.

In one embodiment, one or more neutral wires may be provided between the outer skin layer and the neutral watertight layer.

In one embodiment, the inner semiconducting layer and the outer semiconducting layer may include a thermoplastic resin composition including about 20 wt% to about 40 wt% of carbon black, respectively.

In one embodiment, the skin layer comprises polyethylene, the melting temperature may be about 110 ℃ to about 130 ℃.

The power cable of the present invention is excellent in stability and flexibility at high temperature, excellent in heat resistance, low temperature impact, flexibility, mechanical and electrical properties, and can be recycled, including an insulating layer made of non-crosslinked polypropylene composite resin. The high melting point allows long operation even at high temperatures.

1 is a view showing a power cable according to an embodiment of the present invention.

2 is a cross-sectional view of the power cable of FIG.

Hereinafter, the present invention will be described in detail. In this case, when it is determined that the detailed description of the related known technology or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

The terms to be described below are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators, and the definitions should be made based on the contents throughout the specification for describing the present invention.

1 is a view showing a power cable according to an embodiment of the present invention, Figure 2 is a cross-sectional view of the power cable of FIG.

The power cable 100 with improved flexibility according to an embodiment of the present invention includes one or more conductors (or electrical conductors) 110; An inner semiconducting layer 120 surrounding the conductor 110; An insulating layer 130 surrounding the inner semiconducting layer 120; An outer semiconducting layer 140 surrounding the insulating layer 130; A neutral watertight layer 150 surrounding the outer semiconducting layer 140; And an outer skin layer 160 surrounding the neutral watertight layer 150.

In one embodiment, insulating layer 130 includes reactive polypropylene and polypropylene block copolymers. In one embodiment, the insulating layer 130 is about 30 parts by weight to about 80 parts by weight of the reactive polypropylene and about 20 parts by weight of the polypropylene block copolymer based on 100 parts by weight of the total amount of the reactive polypropylene and the polypropylene block copolymer. To about 70 parts by weight, and a flexural modulus is about 2000 kg / cm ² to about 4000 kg / cm ² . The flexural modulus may be measured based on ASTM D790 standard.

Power cable 100 according to an embodiment of the present invention can transmit a high voltage of 20kV or more, it can be used for a long time stable and eco-friendly resin to stably insulate the conductor 110 provided inside the power cable 100 It comprises an insulating layer 130.

Conductor 110 may be a metallic material that is electrically conductive in a rod or stranded multi-wire. Specifically, it may include aluminum or copper. The conductor may have a circular cross section. The outer diameter of the conductor is about 10mm to about 25mm, the thickness of the insulating layer may be about 6mm to about 8mm. Specifically, the conductor may have a circular cross section, an outer diameter of about 11.4 mm to about 23.5 mm, and an insulating layer may have a thickness of about 6 mm to about 7.5 mm.

Power cable 100 according to an embodiment of the present invention may be provided in a circular shape of the outer diameter of the conductor 10 is about 10mm to about 25mm according to the nominal cross-sectional area. As the nominal cross-sectional area of the power cable 100 increases, the outer diameter of the conductor 110 also increases, thereby increasing the maximum allowable current that can be transmitted. For example, in 22.9kV class environmentally friendly aluminum power cable, the insulation layer thickness can be set to 6.8mm.

In general, the insulation layer thickness can be obtained by the breakdown voltage value and the breakdown strength of the power cable. The criterion for calculating the thickness of the insulation layer can be determined by the larger of the thickness determined from the AC voltage and the thickness determined by the lightning shock voltage. When the thickness of the insulation layer of the 22.9 kV class power cable exceeds about 7.5 mm, the installation of the power cable The workability and workability are deteriorated. Specifically, the thickness of the insulating layer may be about 6.22mm to about 7.37mm.

An inner semiconducting layer 120 is provided on the outer side of the conductor 110, and an outer semiconducting layer 140 is surrounded on the outer side of the inner semiconducting layer 120, between the inner semiconducting layer 120 and the outer semiconducting layer 140. An insulating layer 130 may be interposed therebetween.

Both the inner semiconducting layer 120 and the outer semiconducting layer 140 are semiconducting layers, such as semiconductor layers, which may have a volume resistivity of less than about 500 Ω · m, preferably less than about 20 Ω · m at room temperature. The inner semiconducting layer and the outer semiconducting layer may include a thermoplastic resin composition including about 20 wt% to about 40 wt% of carbon black, respectively. For example, the thermoplastic resin may include a polypropylene polymer. For example, the inner semiconducting layer 120 and the outer semiconducting layer 140 may include a polypropylene polymer in which carbon black of about 20 wt% to about 40 wt% of carbon black is dispersed.

The inner semiconducting layer 120 is interposed between the conductor 110 and the insulating layer 130 so that the inner semiconducting layer 120 can prevent electric field relaxation and partial discharge of the conductor surface. The outer semiconducting layer 140 serves to protect the insulating layer 130 in addition to the electric field relaxation.

The neutral water-tight layer 150 may include a semiconductive swelling tape, and the semiconductive swelling tape may expand (swell) by absorbing moisture.

The outer surface of the neutral watertight layer 150 may be provided to be surrounded by the outer skin layer 160. The outer layer 160 may include polyethylene and may have a melting temperature of about 110 ° C. to about 130 ° C. (melting temperature tested at a temperature increase rate of 20 ° C./min according to KS M ISO 11357-3). Specifically, the melting temperature of the shell layer 160 may be a melting temperature of about 118 ℃ to about 128 ℃.

In an embodiment, when the power cable 100 is installed in the air or the power port, the outer skin layer 160 may be formed by including polyvinyl chloride (PVC) having excellent flame retardancy. In other cases, the shell layer 160 may be formed by including a polyethylene resin having excellent durability.

One or more neutral wires 170 may be provided between the outer skin layer 160 and the neutral water tight layer 150. The neutral wire 170 may be an interlocking wire, and a cross section having an outer diameter of about 0.1 times to about 0.15 times with respect to the outer diameter of the conductor 110 may be provided as a plurality of wires in a circle.

In general, crosslinked polyethylene is used as an insulating layer in a power cable. Since the crosslinked polyethylene crosslinks using an organic peroxide, it is impossible to recycle the crosslinked polyethylene and has a low melting point. In this case, a problem may occur that causes deformation of the power cable. In addition, when the polypropylene is used as the insulating layer of the power cable, the polypropylene has a melting point of about 150 ° C. or higher and is higher than that of crosslinked polyethylene, so that it can be operated at a high temperature, while being vulnerable to low temperature impact resistance and having high rigidity. Due to the lack of flexibility, there is an inadequate disadvantage in laying power cables.

The power cable 100 according to the present invention may include an insulating layer 130 manufactured by blending one or more novel polymer resins. The insulating layer 130 may include a non-crosslinked thermoplastic polymer resin.

The insulating layer 130 includes reactive polypropylene, polypropylene block copolymer, and ionic inorganic material. Insulating layer 130 is more specific to the content ratio of the material constituting the insulating layer 130 to improve the insulation strength and to improve the flexibility, flexibility, etc. during installation of the power cable 100 to facilitate the construction workability It can limit to a range.

In an embodiment, the insulating layer 130 may be manufactured by blending two or more different resins. For example, the different resins may include reactive polypropylene and polypropylene block copolymers. For example, the reactive polypropylene and polypropylene block copolymers can be non-crosslinkable polymers.

The insulating layer 130 is about 30 parts by weight to about 80 parts by weight of the reactive polypropylene and about 20 parts by weight to about 70 parts by weight of the polypropylene block copolymer based on 100 parts by weight of the total of the reactive polypropylene and the polypropylene block copolymer. It includes parts by weight.

In an embodiment, the insulating layer 130 may further include an ionic inorganic material. For example, the insulating layer 130 is about 55 parts by weight to about 65 parts by weight of the reactive polypropylene and about 35 parts by weight of the polypropylene block copolymer based on 100 parts by weight of the total of the reactive polypropylene and the polypropylene block copolymer. To about 45 parts by weight, and about 0 parts by weight to about 0.04 parts by weight (400 ppm) of ionic minerals.

With respect to 100 parts by weight of the total of the reactive polypropylene and the polypropylene block copolymer, the heat resistance of the insulating layer is lowered when the reactive polypropylene is included in an amount of more than about 80 parts by weight, and the heat strain is increased to increase the power cable. Problems such as pressing occurs, and when the content of the reactive polypropylene is less than about 20 parts by weight, flexibility and low temperature impact resistance may be lowered.

When the polypropylene block copolymer is included in less than about 30 parts by weight, the heat resistance of the insulating layer is lowered, and when the polypropylene block copolymer is included in more than about 70 parts by weight, the rigidity of the insulating layer of the present invention is increased. This may cause problems such as low flexibility and whitening.

In one embodiment the reactive polypropylene may comprise ethylene-propylene rubber bonded to a matrix comprising a polypropylene copolymer. In one embodiment, the polypropylene copolymer may be formed by polymerizing one or more olefin comonomers and propylene monomers among α-olefins except ethylene and propylene.

For example, the reactive polypropylene is a polypropylene copolymer formed by polymerizing at least one olefin comonomer selected from ethylene and an α-olefin other than propylene and a propylene monomer in a reactor, and ethylene in a matrix composed of the polypropylene copolymer. Propylene rubber can be formed by chemically or physically bonding.

The insulating layer 130 may further include the ionic inorganic material. The ionic inorganic material may be derived from the residue of the catalyst component used in preparing the insulating layer using the reactive polypropylene and the polypropylene block copolymer, and additives such as antioxidants. For example, the ionic inorganic material may include one or more of magnesium (Mg), aluminum (Al), phosphorus (P), silicon (Si), calcium (Ca), and zinc (Zn).

The ionic inorganic material may be included in an amount of about 0.04 parts by weight or less based on 100 parts by weight of the total of the reactive polypropylene and polypropylene block copolymer. For example, it may be included from about 0 parts by weight to about 0.04 parts by weight. While preventing the whitening of the insulating layer in the content, it may be excellent in mechanical strength and flexibility, such as impact resistance.

In the present invention, ethylene-propylene rubber may be in the form of a heterophasic copolymer. The heterophasic copolymer may be in a form in which rubber domains of ethylene-propylene rubber are dispersed in a matrix made of polypropylene homopolymer or polypropylene copolymer.

In an embodiment of the present invention, a homopolymer means a polymer having one kind of repeating unit, and a copolymer means a polymer having two or more kinds of repeating units different from each other.

For example, the reactive polypropylene may be a heterophasic copolymer, and may be formed by chemically or physically bonding ethylene-propylene rubber in a matrix of the polypropylene copolymer. The α-olefin comonomer except for propylene may be an olefin compound including the structural formula CH ₂ = CH-R. Wherein R may be hydrogen (H) and linear or branched C 2 -C 10 alkyl. For example, the α-olefin may comprise one of 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-tesene, 1-dodecene and mixtures thereof. Can be.

For example, the α-olefin comonomer may comprise ethylene, the polypropylene copolymer is an ethylene-propylene copolymer, and the ethylene-propylene rubber may be branched to the polypropylene copolymer. In addition, the ethylene-propylene copolymer may be a random copolymer in which comonomers are randomly dispersed along the polymer chain.

The polypropylene block copolymer may include about 65 parts by weight to about 82 parts by weight of propylene homopolymer and about 18 parts by weight to about 35 parts by weight of ethylene-propylene rubber. When included in the content range may be excellent mechanical properties such as moldability, dimensional stability and impact resistance of the present invention.

The ethylene-propylene rubber may include about 25% to about 50% by weight of ethylene based on the total weight. When included in the content range, while excellent in moldability of the present invention, mechanical properties such as impact resistance may be excellent.

Melting point of the reactive polypropylene is about 160 ℃ or more, melt enthalpy is about 20 J / g or more, melt index measured by applying a 2.16kg load at 230 ℃ according to ASTM D1238 standard is about 0.5g / 10min to about 1.5 g / 10 min. Specifically, the melting point of the reactive polypropylene is about 160 ° C to about 170 ° C, the melting enthalpy is about 20J / g to about 30J / g, and the melt index may be about 0.7g / 10min to about 0.9g / 10min. . The compatibility, formability and mechanical strength of the present invention may be excellent in the melting point, melting enthalpy and melt index of the above range.

The melting point of the polypropylene block copolymer is about 160 ℃ or more, the melt enthalpy is about 50 J / g to about 70 J / g, the melt index measured by applying a 2.16kg load at 230 ℃ according to ASTM D1238 standard is about 2.5g / 10min to about 3.5g / 10min. The compatibility, formability and mechanical strength of the present invention may be excellent in the melting point, melting enthalpy and melt index of the above range.

The ethylene-propylene rubber included in the reactive polypropylene may be the same as the ethylene-propylene rubber included in the polypropylene block copolymer. The insulating layer may be prepared by blending a reactive polypropylene and a polypropylene block copolymer. In this case, the ethylene-propylene rubber included in the reactive polypropylene and the polypropylene block copolymer may be used as the same material to improve the compatibility to improve mechanical properties. In addition, by using the same ethylene-propylene rubber, the reactive polypropylene and the polypropylene block copolymer are uniformly mixed, thereby realizing excellent electrical characteristics at the interface of the insulating layer.

For example, the flexural modulus measured according to the ASTM D790 standard of the reactive polypropylene is about 500 kg / cm ² to about 1500 kg / cm ² , and the flexural modulus measured according to the ASTM D790 standard of the polypropylene block copolymer. modulus of elasticity may be about 8500 kg / cm ² and about 9500kg / cm ^2. In this embodiment, when the flexural modulus of the reactive polypropylene and polypropylene block copolymer is within the aforementioned range, the flexural modulus of the insulating layer 130 is about 2000 kg / cm ^2. It can be controlled within the range of about 4000kg / cm ² , thereby improving the predetermined physical properties, such as mechanical strength, flexibility of the power cable 100. For example, the flexural modulus measured according to ASTM D790 standard of the reactive polypropylene is 1000 kg / cm ² , and the flexural modulus measured according to ASTM D790 standard of the polypropylene block copolymer is 9000 kg / cm ² days. Can be.

In one embodiment of the invention, the flexibility of the power cable 100 may be affected by the insulating layer 130, the flexibility of the power cable 100 of the insulating layer 130 measured according to the ASTM D790 standard Flexural modulus is about 2000kg / cm ² Preferably from about 4000 kg / cm ² . The insulating layer 130 may be formed by mixing the reactive polypropylene and the polypropylene block copolymer, and together with the flexural modulus of each of the reactive polypropylene and the polypropylene block copolymer, a mixing ratio, a mixing method, and the like. By this, the flexural modulus of the insulating layer 130 can be controlled.

Meanwhile, in the power cable 100 according to the present invention, the inner semiconducting layer 120, the insulating layer 130, the outer semiconducting layer 140, and the neutral watertight layer 150 are insulated from the conductor 110 provided therein. It is provided to improve the electrical characteristics, the outer layer 160 may be provided to maintain the mechanical strength of the power cable 100, such as environmental resistance, corrosion resistance, impact resistance in low temperature and high temperature environment. Among these, the inner semiconducting layer 120, the insulating layer 130, and the outer semiconducting layer 140 affect the flexibility of the power cable 100, and the insulating layer 130 having the thickest thickness among them is The power cable 100 may have the greatest influence on the flexibility.

Therefore, it is preferable to maintain the flexural modulus of the insulating layer 130 in a predetermined range. Insulating layer 130 in the embodiment has a flexural modulus of about 2000kg / cm ² and about 4000kg / cm ² measured according to ASTM D790 standard to be. When the flexural modulus of the insulating layer 130 is less than about 2000 kg / cm ² , the heating strain is large, and the power cable using the insulating layer is pressed to interfere with the flow of electricity. When the elastic modulus is greater than about 4000 kg / cm ² , the rigidity is high and the flexibility is high. It may be difficult to bend the power cable due to deterioration, which may cause problems during cable construction work.

In this embodiment, the melting point of the insulating layer 130 may be about 160 ℃ to about 170 ℃. Specifically, the melting point of the insulating layer 130 may be about 160 ° C. or more, and more specifically, about 160 ° C. to about 170 ° C.

In addition, the power cable 100 according to the present embodiment by using an insulating layer made of a non-crosslinked polymer composite resin, can be recycled, environmentally friendly, and stable operation even when the transmission point is increased by increasing the melting point It may be possible.

Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. However, this is presented as a preferred example of the present invention and in no sense can be construed as limiting the present invention.

Example  And Comparative example

Example  One

As shown in Table 1 below, 60 parts by weight of reactive polypropylene (product name: Hifax CA 7441A, Lyondellbasell), 40 parts by weight of polypropylene block copolymer (product name: CF335, Hanwha Total) and 0.04 weight of ionic minerals An insulating layer for a power cable containing less than or equal to was prepared.

Example  2

An insulating layer was prepared in the same manner as in Example 1, except that the content of the reactive polypropylene and the polypropylene block copolymer was applied as described in Table 1 below.

Comparative example  One

An insulating layer was prepared in the same manner as in Example 1, except that only reactive polypropylene was applied as shown in Table 1 below.

Comparative example  2

An insulating layer was manufactured in the same manner as in Example 1, except that only the polypropylene block copolymer was applied as in Table 1 below.

Comparative example  3

An insulating layer was prepared in the same manner as in Example 1, except that the content of the reactive polypropylene and the polypropylene block copolymer was applied as described in Table 1 below.

Comparative example  4

An insulating layer was prepared in the same manner as in Example 1, except that crosslinked polyethylene (XLPE, borealis, Inc.) was applied.

For the insulating layers of Examples 1 to 2 and Comparative Examples 1 to 4, power cables were manufactured under the conditions shown in Table 2 below, and the mechanical properties of the insulating layer and the power cables were measured according to the following criteria. Are shown in Tables 3 and 4 below.

Property measurement method

(1) Evaluation of mechanical properties at room temperature and after heating: For each of the power cable specimens manufactured in Examples and Comparative Examples, tensile strength and elongation at break point were determined at a tensile speed of 25 mm / min at room temperature according to IEC-60811-501. Measured. Heating was performed at 135 ° C. for 240 hours, and tensile strength and elongation at break were measured at a tensile speed of 25 mm / min.

On the other hand, in the case of power cables, the tensile strength after room temperature and heating should be 1.27kg / mm2 or more and elongation should be 350% or more.

(2) Heating deformation: When the insulation layer specimens prepared in the above Examples and Comparative Examples were tested by applying a constant load at a heating temperature of 130 ° C. for 6 hours according to the IEC-60811-508 standard, the thickness reduction rate was It should satisfy 50% or less.

(3) Cold resistance test: Five insulation resistance tests were carried out at -40 ° C according to KS C 3004 for each insulation layer specimen prepared in the above Examples and Comparative Examples, and the failure phenomenon of the five specimens was observed. The more breakage does not occur, the better the cold resistance.

(4) Flexural modulus test: The flexural modulus was measured according to ASTM D790 standard for each insulation layer specimen prepared in Examples and Comparative Examples, and the flexural modulus at 2000kg / cm 2 to 4000kg / cm 2 was measured at low temperature impact resistance, It is judged to be excellent in flexibility and flexibility.

Referring to Tables 1 to 4, in the case of Comparative Example 1 was excellent in cold resistance, flexural modulus, but too flexible, it was confirmed that the heat deformation characteristics are inadequate, Comparative Example 2 has excellent electrical properties but at low temperatures Improper impact and rigidity were found to be inadequate for flexibility and cable bendability. In addition, Comparative Example 3 was confirmed that the flexural modulus value is improved compared to Comparative Example 2 to improve the flexibility, but the impact resistance at low temperature is inadequate.

In the case of using the reactive polypropylene alone as an insulating layer as in Comparative Example 1, it was confirmed that the heat deformation characteristics were deteriorated, so that the insulation layer of the power cable was pressed to be inadequate, and as shown in Comparative Example 2, the polypropylene block copolymer was used. When used alone, it was confirmed that the electrical properties are excellent, but the impact resistance at low temperatures is reduced and the flexibility is low. In addition, in the case of including the reactive polypropylene and polypropylene block copolymer in a content outside the scope of the present invention as in Comparative Example 3, it was confirmed that the impact resistance at low temperature is reduced.

That is, as the insulating layer of the power cable, it is preferable to use a reactive polypropylene and a polypropylene block copolymer as in Examples 1 and 2, wherein the reactive polypropylene and polypropylene block copolymer are used. It was confirmed that mixing in a predetermined controlled range can secure both electrical characteristics, mechanical strength, and flexibility.

When the polymer resin according to the present embodiment is applied as an insulating layer of a power cable, the conductor can be operated at a maximum allowable temperature of 110 ° C. at all times and excellent impact resistance can be secured at a low temperature of −40 ° C. In addition, the reactive polypropylene and polypropylene block copolymers, which are components of the insulating layer according to the present embodiment, are non-crosslinkable polymers, and when used as an insulating layer of a power cable, flexibility, mechanical and electrical properties are improved and non-crosslinking, which is environmentally friendly. Power cable can be provided.

Those skilled in the art will appreciate that the present invention can be embodied in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive. The scope of the present invention is indicated by the scope of the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and the equivalent concept are included in the scope of the present invention. Should be interpreted.

Claims (14)

One or more conductors; An inner semiconducting layer surrounding the conductor; An insulating layer surrounding the inner semiconducting layer; An outer semiconducting layer surrounding the insulating layer; A neutral watertight layer surrounding the outer semiconducting layer; And It includes; outer shell layer surrounding the neutral watertight layer; The insulating layer is about 30 parts by weight to about 80 parts by weight of the reactive polypropylene and about 20 parts by weight of the polypropylene block copolymer based on 100 parts by weight of the total amount of the reactor based polypropylene and the polypropylene block copolymer. To about 70 parts by weight, The insulation layer has a flexural modulus of about 2000kg / cm ² to about 4000kg / cm ² . The power cable according to claim 1, wherein the flexural modulus is measured according to ASTM D790 standard. The method of claim 1, wherein the insulating layer further comprises an ionic inorganic, For 100 parts by weight of the sum of the reactive polypropylene and polypropylene block copolymer, A power cable comprising from about 55 parts by weight to about 65 parts by weight of reactive polypropylene, about 35 parts by weight to about 45 parts by weight, and about 0.04 parts by weight or less of ionic minerals. The polypropylene copolymer of claim 1, wherein the reactive polypropylene comprises a polypropylene copolymer formed by polymerizing at least one olefin comonomer selected from α-olefins other than ethylene and propylene and a propylene monomer in a reactor, and the polypropylene copolymer. A power cable formed by chemically or physically bonding ethylene-propylene rubber in a matrix. The ethylene-propylene block copolymer of claim 1, wherein the polypropylene block copolymer is formed by polymerizing about 65 parts by weight to about 82 parts by weight of propylene homopolymer, and about 18 parts by weight to about 35 parts by weight of ethylene-propylene rubber. Including, And about 25 wt% to about 50 wt% of ethylene relative to the total weight of the ethylene-propylene rubber. The power cable of claim 1, wherein the melting point of the reactive polypropylene is about 160 ° C. or more, a melting enthalpy of about 20 J / g or more, and a melt index of about 0.5 g / 10 min to about 1.5 g / 10 min. The method of claim 6, wherein the melting point of the reactive polypropylene is about 160 ° C. to about 170 ° C., the melt enthalpy is about 20 J / g to about 30 J / g, and the melt index is about 0.7 g / 10 min to about 0.9 g /. 10min power cable. The method of claim 1, wherein the polypropylene block copolymer has a melting point of about 160 ° C. or more, a melting enthalpy of about 50 J / g to about 70 J / g, and a melting index of about 2.5 g / 10 min to about 3.5 g / 10 min. Power cable. According to claim 1, Flexural modulus measured according to the ASTM D790 standard of the reactive polypropylene is about 500kg / cm ² to about 1500kg / cm ² The flexural modulus measured according to ASTM D790 standard of the polypropylene block copolymer is about 8500kg / cm ² to about 9500kg / cm ² power cable. The method of claim 9, wherein the flexural modulus measured according to the ASTM D790 standard of the reactive polypropylene is about 1000kg / cm ² , the flexural modulus measured according to the ASTM D790 standard of the polypropylene block copolymer is about 9000kg / cm ² of power cable. The power cable of claim 1, wherein the melting point of the insulating layer is about 160 ° C. to about 170 ° C. 7. The power cable of claim 1, wherein one or more neutral wires are provided between the outer skin layer and the neutral wire watertight layer. The power cable of claim 1, wherein the inner semiconducting layer and the outer semiconducting layer each comprise a thermoplastic resin composition comprising about 20% to about 40% by weight of carbon black. The power cable of claim 1 wherein the sheath layer comprises polyethylene and has a melting temperature of about 110 ° C. to about 130 ° C. 7.

Images