KR102082674B1 - Power cable with insulation layer having excellent transparence - Google Patents

Abstract

The present invention relates to a power cable having an insulation layer with improved transparency. 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 polypropylene block copolymer and ethylene-octene rubber.

Description

Power cable with insulation layer with improved transparency {POWER CABLE WITH INSULATION LAYER HAVING EXCELLENT TRANSPARENCE}

The present invention relates to a power cable. More particularly, the present invention relates to a power cable having an insulating layer capable of long-term operation at high temperature while improving transparency and reducing whitening.

In general, 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 organic peroxide or silane (US Patent No. 6284178 (2011.09.04)) as a medium (US Patent No. 4426497 (1984.01.17)) In recent years, in the large cable industry, a crosslinking type using organic peroxide is most widely used.

In recent years, power cable characteristics that can be recycled and have high transmission capacity are required. In order to satisfy this requirement, an electric wire including an insulating layer made of an uncrosslinked polymer resin capable of operating at a maximum allowable temperature of 110 ° C is required.

On the other hand, crosslinked polyethylene resins are thermoset resins prepared by crosslinking polyethylene, and thus are not recycled, and thus are difficult to dispose, 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 currently mainly used, is a problem because it is not suitable for use in power cable insulation materials due to its insufficient heat resistance.

Against this backdrop, Korean Patent Publication No. 10-2010-0106871 (2010.10.04) discloses a prior art for non-crosslinked polyethylene resin as an insulating material for power cables, but due to the low shear thinning of the resin in actual processing. There is a problem that poor workability occurs processing. 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 non-crosslinking insulating layer that can be recycled.

Another object of the present invention is to provide a power cable including an insulating layer made of a non-crosslinkable resin having excellent heat resistance, low temperature impact, mechanical and electrical properties, and excellent whitening and transparency.

Still another object of the present invention is to provide a power cable having excellent electrical characteristics with a lower catalyst residual amount than a general polypropylene composite resin.

One aspect of the present invention relates to a power cable having an insulation layer having improved transparency. 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 comprises a polypropylene block copolymer and an ethylene-octene rubber, and the insulating layer is a total of 100 weights of the polypropylene block copolymer and the ethylene-octene rubber. To about 30 parts by weight to 80 parts by weight of polypropylene block copolymer and 20 parts by weight to 70 parts by weight of ethylene-octene rubber, wherein the insulation layer has a haze of 90% or less or a total transmittance. ) Is more than 80%.

In one embodiment, the haze and light transmittance may be measured based on ASTM D 1003.

In one embodiment, the insulating layer further comprises an ionic inorganic, 55 parts by weight to 65 parts by weight of polypropylene block copolymer, ethylene- based on 100 parts by weight of the total of the polypropylene block copolymer and ethylene-octene rubber It may include 35 parts by weight to 45 parts by weight of octene rubber and 0.03 parts by weight or less of ionic inorganic materials.

In one embodiment, the polypropylene block copolymer may include 80 to 95 parts by weight of ethylene-propylene random copolymer and 5 to 20 parts by weight of ethylene-propylene rubber polymerized with ethylene-propylene random block copolymer. have.

In one embodiment, the ethylene content in the ethylene-propylene random copolymer is 0.5% to 10% by weight, the ethylene content in the ethylene-propylene rubber is 20% to 60% by weight, and the ethylene-propylene random copolymer The intrinsic viscosity ratio of the solvent extract of ethylene-propylene rubber (xylene is a solvent) relative to the intrinsic viscosity may be 0.5 to 1.1.

In one embodiment, the polypropylene block copolymer has a melt index (MI) of 1 g / 10 min to 10 g / 10 min measured according to ASTM D 1238 (230 ° C., 2.16 kg), and a cloudy measured according to ASTM D 1003. The degree may be 5% or less.

In one embodiment, the polypropylene block copolymer may include a form in which ethylene-propylene rubber having a size of 0.4 μm or less is dispersed in a matrix including an ethylene-propylene random block copolymer.

In one embodiment, the polypropylene block copolymer has a flexural modulus of 7000 kg / cm 2 to 10000 kg / cm 2 measured according to ASTM D790 standard, and a heat distortion temperature measured according to ASTM D648 standard is 90 ° C. to 105 ° C., Melting point may be 154 ℃ to 156 ℃.

In one embodiment, the polypropylene block copolymer has a Rockwell hardness of 55 to 63, and a 1/8 "notched Izod impact strength measured by ASTM D256 standard is 10kgcm / cm to 20kgcm can be / cm.

In one embodiment, the ethylene-octene rubber is a copolymer of ethylene monomer and 1-octene comonomer, and the content of 1-octene comonomer in the ethylene-octene rubber is 5 wt% to 40 wt%, ASTM D 1238 The melt index (MI) measured based on (230 ° C., 2.16 kg) may be 6 g / 10 min or less.

In one embodiment, the melting point of the insulating layer is 140 ℃ to 160 ℃, the flexural modulus measured according to the ASTM D790 standard may be 2000kg / ㎠ to 4000kg / ㎠.

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

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

In one embodiment, the outer layer includes polyethylene, the melting temperature may be 110 ℃ to 130 ℃.

According to the present invention can provide a power cable having an eco-friendly non-crosslinking insulating layer that can be recycled.

In addition, according to the present invention, it is possible to provide a power cable including an insulating layer made of a non-crosslinkable resin having excellent heat resistance, low temperature impact, mechanical and electrical properties, and excellent whitening and transparency.

In addition, according to the present invention it is possible to provide a power cable excellent in electrical characteristics with a low catalyst residual amount than the general polypropylene composite resin.

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.
Figure 3a is a view showing the stress whitening results after the orientation crystallization according to Example 1 of the present invention, Figure 3b is a view showing the stress whitening results after the orientation crystallization according to Example 2 of the present invention.
Figure 4a is a view showing the stress whitening results after the orientation crystallization according to Comparative Example 1, Figure 4b is a view showing the stress whitening results after the orientation crystallization according to Comparative Example 2, Figure 4c is a stress after the orientation crystallization according to Comparative Example 3 The figure which showed the whitening result.
5A shows a power cable according to Embodiment 1 of the present invention, and FIG. 5B shows a power cable according to Comparative Example 1 to the present invention.

Hereinafter, the present invention will be described in detail. In this case, in the following description of the present invention, if 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. Power cable 100 having an improved insulation layer according to an embodiment of the present invention comprises 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 shell layer 160 surrounding the neutral watertight layer 150, wherein the insulating layer 130 includes a polypropylene block copolymer and ethylene-octene rubber, and the insulating layer 130 is a polypropylene block copolymer. And 30 parts by weight to 80 parts by weight of polypropylene block copolymer and 20 parts by weight to 70 parts by weight of ethylene-octene rubber with respect to 100 parts by weight of the total amount of ethylene-octene rubber, and the insulating layer 130 is haze. ) Is 90% or less, or 80% or more in total transmittance.

In one embodiment, the haze and light transmittance may be measured based on ASTM D 1003.

Power cable 100 according to an embodiment of the present invention can transmit a high voltage of 20kV or more, can be used for a long time stably and the environmentally friendly resin to stably insulate the conductor 110 provided therein as the insulating layer 130 It may include.

The electrical conductor 110 may be a metallic material that is electrically conductive in a rod or stranded multi-wire, and may specifically include aluminum or copper. The conductor 110 may have a circular cross-section having an outer diameter of 10 mm to 25 mm, and a thickness of the insulating layer 130 may be 6 mm to 8 mm. Specifically, the cross-sectional area of the conductor 110 may have a circular outer diameter of 11.4 mm to 23.5 mm, and the thickness of the insulating layer 130 may be 6 mm to 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 110 is 10mm to 25mm according to the nominal cross-sectional area, the larger the nominal cross-sectional area of the power cable 100 conductor ( The outer diameter of the 110 is also increased, thereby increasing the maximum allowable current that can be transmitted.

For example, in the 22.9 kV class eco-friendly solid aluminum power cable 100, the thickness of the insulating layer may be set to 6.8 mm, the thickness of the insulating layer 130 can be obtained by the breakdown voltage value and the breakdown strength of the cable. have. The criterion for calculating the thickness of the insulation layer is determined by the greater of the thickness determined from the AC voltage and the thickness determined from the lightning shock voltage. When the insulation thickness of the 22.9 kV class power cable 100 exceeds 8 mm, the installation of the power cable is performed. The workability and workability are deteriorated. Specifically, the thickness of the insulating layer 110 may be 6.22mm to 7.37mm.

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

The inner semiconducting layer 120 and the outer semiconducting layer 140 are semiconducting layers, for example, semiconductor layers, both of which may have a volume resistivity of less than 500 Ω · m, preferably less than 20 mA · m at room temperature. In the example, the inner semiconducting layer 120 and the outer semiconducting layer 140 may include a thermoplastic resin composition including 20 wt% to 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 be provided with 20 wt% to 40 wt% of carbon black dispersed in the polypropylene polymer, respectively.

The inner semiconducting layer 120 may be interposed between the conductor 110 and the insulating layer 130. The inner semiconducting layer 120 may prevent electric field relaxation and partial discharge of the conductor surface, and the outer semiconducting layer 140 serves to protect the insulating layer together with the electric field relaxation. The neutral water-tight layer 150 may include a semiconductive inflation tape, and the semiconductive inflation tape may expand (swell) by absorbing moisture.

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

The power cable 100 is made of polyvinyl chloride (PVC) or the like, which is excellent in flame retardancy when installed in air or a power port, and in other cases, the polyethylene having excellent durability as the outer layer 160. (PE) is used.

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 to 0.15 times the outer diameter of the conductor 110 may be provided including a plurality of wires in a circular shape.

In general, crosslinked polyethylene is used as an insulating layer in a power cable. The crosslinked polyethylene crosslinks using an organic peroxide, and thus, the crosslinked polyethylene cannot be recycled and its melting point is low. This may cause problems such as deformation and melting 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 150 ° C. or higher and is higher than that of the crosslinked polyethylene, so that it can be operated at high temperature, but is vulnerable to low temperature impact resistance and high rigidity. There is a lack of flexibility which makes it unsuitable for laying power cables.

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

The insulating layer 130 may be prepared by blending two different resins, for example, different resins may include polypropylene block copolymer and ethylene-octene rubber, and the polypropylene block copolymer and ethylene- The octene rubber can be a non-crosslinkable polymer.

In an embodiment, the insulating layer 130 may further include an ionic inorganic material. For example, the insulating layer 130 is 30 parts by weight to 80 parts by weight of polypropylene block copolymer and 20 parts by weight to 70 parts by weight of ethylene-octene rubber based on 100 parts by weight of the total amount of polypropylene block copolymer and ethylene-octene rubber. And ionic minerals of 0.03 parts by weight or less.

When the polypropylene block copolymer is included in an amount of more than 80 parts by weight based on 100 parts by weight of the polypropylene block copolymer and the ethylene-octene rubber, the mechanical strength of the power cable 100 is increased while the flexibility is decreased. If the polypropylene block copolymer is included in less than 30 parts by weight, the heating strain is increased to cause a phenomenon such as the power cable is pressed.

With respect to a total of 100 parts by weight of the polypropylene block copolymer and ethylene-octene rubber, when the ethylene-octene rubber is included in less than 20 parts by weight, flexibility is reduced, so that it is difficult to change the shape of the power cable, various applications are difficult, and the ethylene When the octene rubber is contained in an amount of more than 70 parts by weight, mechanical strength such as corrosion resistance and weather resistance is lowered.

In addition, in order to further improve the electrical insulating properties of the insulating layer 130 and to suppress the whitening phenomenon, and at the same time to improve the process efficiency, it may be limited to a more specific range, preferably the insulating layer 130 is polypropylene 55 parts by weight to 65 parts by weight of polypropylene block copolymer, 35 parts by weight to 45 parts by weight of ethylene-octene rubber and greater than 0 and 0.03 parts by weight or less based on 100 parts by weight of the block copolymer and the ethylene-octene rubber. More preferably, it may comprise 60 parts by weight of polypropylene block copolymer, 40 parts by weight of ethylene-octene rubber and 0.03 parts by weight of ionic inorganic material.

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 insulation layer using the polypropylene block copolymer and the ethylene-octene rubber, 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 more than 0 and no more than 0.03 parts by weight based on 100 parts by weight of the sum of the polypropylene block copolymer and the ethylene-octene rubber. For example, it may be included in 0 to 0.03 parts by weight. When it is included in the above range, it is not electric field concentration due to fine foreign matter and voids, it is excellent in electrical properties, mechanical strength and flexibility such as impact resistance can be excellent.

The whitening phenomenon is caused by a crack caused by micro voids, and when the whitening phenomenon occurs, the physical properties are drastically reduced, such as transparency decreases, whitening resistance, and impact resistance. Specifically, when the content of the ionic inorganic matters is increased, the electrical performance of the power cable is lowered by lowering the insulation performance, and when the power cable is operated at a high temperature, the life of the power cable is reduced, such as promoting degradation of the power cable. Cause.

On the other hand, the insulating layer according to an embodiment of the present invention can reduce the crystal size of the insulating layer polymer resin including the polypropylene block copolymer and ethylene-octene rubber to improve the light transmittance to suppress the occurrence of whitening phenomenon.

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 type of repeating unit, and a copolymer means a polymer having two or more types of repeating units different from each other.

In one embodiment, the polypropylene block copolymer is an ethylene-propylene random block copolymer in which 80 parts by weight to 95 parts by weight of ethylene-propylene random copolymer and 5 parts by weight to 20 parts by weight of ethylene-propylene rubber are polymerized stepwise in a reactor. It may comprise a polymer.

The ethylene-propylene copolymer may be polymerized by simultaneously introducing ethylene and propylene in a polymerization reactor. The polymerization method of the ethylene-propylene copolymer may be prepared by a method known in the art.

The ethylene-propylene rubber is polymerized in the presence of the ethylene-propylene random copolymer in a series of polymerization reactors following the preparation of the ethylene-propylene random copolymer. The polymerization method of the ethylene-propylene rubber may be prepared by a method known in the art.

When the ethylene-propylene random copolymer is included in an amount of less than 80 parts by weight based on the total weight of the polypropylene block copolymer, the crystallinity of the polypropylene block copolymer resin is lowered so that the heat resistance is lowered. If so, the impact resistance is sharply lowered.

The ethylene content in the ethylene-propylene random copolymer may be included in the 0.5 wt% to 10 wt%. When the ethylene is included in less than 0.5% by weight, the degree of crystallinity of the copolymer may be increased or the compatibility with ethylene-propylene rubber may be lowered, thereby decreasing transparency and whitening resistance, and the degree of crystallinity when the ethylene is included in excess of 10% by weight. Decreases rapidly and mechanical strength such as heat resistance decreases.

Ethylene in the ethylene-propylene rubber may be included 20 to 60% by weight. When the ethylene is included in less than 20% by weight, the physical properties such as elasticity and impact resistance may be degraded, and when included in excess of 60% by weight, the flexibility of the ethylene-propylene rubber may be reduced.

In specific embodiments, the intrinsic viscosity ratio of the solvent extract of ethylene-propylene rubber (xylene is a solvent) to the intrinsic viscosity of the ethylene-propylene random copolymer (intrinsic viscosity of the solvent extract of ethylene-propylene rubber / ethylene-propylene random copolymer) Intrinsic viscosity of the polymer) may be 0.5 to 1.1. When the intrinsic viscosity ratio is out of the above range, the compatibility between the ethylene-propylene random block copolymer and the ethylene-propylene rubber may be reduced, and the moldability of the product may be reduced by agglomeration of the ethylene-propylene rubber and the like. .

The polypropylene block copolymer is a matrix comprising an ethylene-propylene random block copolymer, in which ethylene-propylene rubber having a size of 0.4 μm or less, preferably 0.01 μm to 0.4 μm, in which fine particles are dispersed in the matrix. It may include a form. When the size of the ethylene-propylene rubber is more than 0.4 μm, the moldability may be lowered and a dispersion phase larger than the visible light wavelength may be increased, thereby decreasing transparency.

On the other hand, in the present specification, the "size" may mean the "maximum length" of the ethylene-propylene rubber.

In embodiments, the polypropylene block copolymer has a melt index (MI) of 1 g / 10 min to 10 g / 10 min, measured according to ASTM D 1238 (230 ° C., 2.16 kg), and a cloudyness measured according to ASTM D 1003. May be 5% or less. When the melt index (MI) is less than 1g / 10min, the fluidity is lowered, so it is not suitable to manufacture the power cable by molding, and when it exceeds 10g / 10min, the viscosity is too low to control the thickness of the manufactured power cable uniformly. .

The polypropylene block copolymer has a flexural modulus of 7000 kg / cm 2 to 10000 kg / cm 2 measured according to ASTM D790 standard, and a heat deformation temperature of 90 ° C. to 105 ° C. measured according to ASTM D648 standard, and a melting point of 154 ° C. To 156 ° C. In one embodiment, the polypropylene block copolymer has a Rockwell hardness of 55 to 63, and a 1/8 "notched Izod impact strength measured by ASTM D256 standard is 10kgcm / cm to 20kgcm can be / cm.

The insulating layer 130 may be prepared by mixing the polypropylene block copolymer and ethylene-octene rubber at a predetermined ratio. The ethylene-octene rubber is a copolymer of an ethylene monomer and a 1-octene comonomer, and the content of 1-octene comonomer in the ethylene-octene rubber is 5% to 40% by weight, ASTM D 1238 (230 ° C., 2.16 kg) may have a melt index (MI) of 6 g / 10 min or less. Specifically, the content of the 1-octene comonomer in the ethylene-octene rubber may be 5.5 wt%, 7.6 wt%, 28 wt% and 39 wt%. In addition, the glass transition temperature (Tg) of the ethylene-octene rubber may be -30 ° C or less.

If the melt index of the ethylene-octene rubber is higher than 6g / 10min, the melt index of the insulating layer is increased, which is a problem in processing the power cable, and when the glass transition temperature is higher than -30 ° C, the low temperature characteristic of the power cable Lowers the problem.

Since the ethylene-octene rubber is a copolymer of ethylene and octene and has excellent low-temperature impact strength compared to ethylene-propylene-diene-based elastomers (EPDM), when the insulating layer 130 is manufactured by mixing with the polypropylene block copolymer The low temperature impact strength can be improved and mechanical properties can be further improved.

In one embodiment of the present invention, the flexibility of the power cable 100 may be affected by the insulating layer 130, the flexibility of the power cable 100 based on the ASTM D790 standard of the insulating layer 130 It is preferable that the measured flexural modulus is 2000 kg / cm 2 to 4000 kg / cm 2. The insulating layer 130 may be formed by mixing a polypropylene block copolymer and ethylene-octene rubber, and these polypropylene block copolymers and ethylene-octene rubber may be combined with respective flexural modulus, mixing ratio, and mixing method. For example, the flexural modulus of the insulating layer 130 may be controlled.

Melting point of the insulating layer 130 is 140 ℃ to 160 ℃, the flexural modulus measured according to the ASTM D790 standard may be 2000kg / ㎠ to 4000kg / ㎠. If the flexural modulus of the insulating layer 130 is more than 4000kg / ㎠, the rigidity is high, the flexibility is lowered, the problem is caused by whitening phenomenon, etc., if less than 2000kg / ㎠ the heating strain is large, such as the power cable is pressed This can happen.

In this embodiment, the melting point of the insulating layer 130 may be 140 ℃ to 160 ℃. Specifically, the melting point of the insulating layer 130 may be 150 ° C. or more, and more specifically 150 ° C. to 160 ° C. In one embodiment, the melting point of the insulating layer 130 may be 152 ° C or 153 ° C. If the melting point of the insulating layer 130 is less than 150 ℃ can suppress the occurrence of whitening phenomenon, but it is difficult to operate the power cable 130 for a long time stably, if it exceeds 160 ℃ of the polymer resin constituting the insulating layer There is a problem that a large number of bleaching occurs due to the large crystal size. Therefore, in order to stably operate the power cable 100 at a high temperature and to control the occurrence of bleaching within a predetermined range, the melting point of the insulating layer 130 is preferably 150 ° C to 160 ° 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, it is possible to recycle and environmentally friendly, and also stable operation even when the transmission capacity is increased by increasing the melting point It is 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, it is presented as a preferred example of the present invention and should not be construed as limiting the present invention by any means.

Example  And Comparative example

Example  One

As shown in Table 1 below, 60 parts by weight of a polypropylene block copolymer (product name: CF309, Hanwha Total) and 40 parts by weight of ethylene-octene rubber (product: Engage 8842, Dow Elastomes) and 0.0180 part by weight of ionic minerals An insulating layer for an insulated cable was prepared.

Example  2 ~ 3

An insulating layer was prepared in the same manner as in Example 1, except that reactive polypropylene and ethylene-octene rubber contents were 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 the content of reactive polypropylene and ethylene-octene rubber was applied as shown in Table 1 below.

Comparative example  2

As described in Table 1, except that 60 parts by weight of random polypropylene-based polymer (RP242G, Lyondellbasell, Inc.) and 40 parts by weight of reactive polypropylene (Product name: CA7441A, Lyondellbasell, Inc.) were applied in the same manner as in Comparative Example 1 An insulating layer was prepared.

Comparative example  3

An insulating layer was prepared in the same manner as in Comparative Example 1, except that 100 parts by weight of a random polypropylene-based polymer (RP242G, Lyondellbasell, Inc.) was applied as described in Table 1 below.

Comparative example  4

An insulating layer was prepared in the same manner as in Comparative Example 1, except that crosslinked polyethylene (LS4201, Borealis, Inc.) was applied.

For the insulating layers of Examples 1 to 3 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 Table 1, Table 3 and Table 4.

Property measurement method

(1) Evaluation of mechanical properties at room temperature and after heating: For each power cable specimen prepared in Examples and Comparative Examples, the tensile strength and elongation at break point were measured at a tensile speed of 25 mm / min at room temperature according to IEC-60811-501. Measured. The heating was performed at 135 ° C. for 240 hours, and the tensile strength and elongation at break were measured at a tensile speed of 25 mm / min. 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: The thickness reduction rate of each insulation layer specimens prepared in Examples and Comparative Examples is 50% when a constant load is applied under the condition of heating temperature of 130 ℃ and 6 hours according to IEC-60811-508 standard. Should be less than or equal to%

(3) Cold resistance test: Five insulation resistance tests were carried out at -40 ° C according to KS C 3004 specification for each insulation layer specimens prepared in Examples and Comparative Examples, and the failure phenomenon of five specimens was observed. The less breakage occurs, the better the cold resistance.

(4) Flexural modulus test: The flexural modulus was measured according to ASTM D790 standard for the insulating layer and the comparative example, and when the flexural modulus was 2000kg / cm 2 to 4000kg / cm 2, it was excellent in low temperature impact resistance, flexibility, and flexibility. Judging.

(5) Stress-whitening: The Example and Comparative Example insulation layer specimens were bent at 90 ° C to visually check for whitening and cracks.

(6) Orientation-induced crystallization: Orientation of the specimens with the universal testing machine (UTM) with respect to the insulating layer of the above Examples and Comparative Examples and visually confirmed the presence of whitening and cracks.

(7) Haze and Total Transmittance

For the Example and Comparative Example insulating layers, 0.5mm thick specimens were fabricated using a hot press machine according to ASTM D 1003, and then the light diffusivity (Haze) and the total transmittance (Total Transmittance) were measured. It is shown in Table 1 below. The hazemeter (NDH-5000) was used for the test equipment, and white LED was used as a light source. A test beam of 14 mm ￠ and an entrance opening of 25 mm ￠ were used.

Figure 3a is a view showing the stress whitening results after the orientation crystallization according to Example 1 of the present invention, Figure 3b is a view showing the stress whitening results after the orientation crystallization according to Example 2 of the present invention. Figure 4a is a view showing the stress whitening results after the orientation crystallization according to Comparative Example 1, Figure 4b is a view showing the stress whitening results after the orientation crystallization according to Comparative Example 2, Figure 4c is a stress after the orientation crystallization according to Comparative Example 3 The figure which showed the whitening result. In addition, Figure 5a shows a power cable according to Example 1 of the present invention, Figure 5b shows a power cable of Comparative Example 1 with respect to the present invention.

Referring to Tables 1 to 4 together with Figures 3a to 5b, in the case of Examples 1 to 3, the whitening phenomenon did not occur, Comparative Example 1 is excellent in electrical properties but inadequate impact resistance at low temperatures Whitening phenomenon occurred after stress whitening and orientation crystallization. Comparative Example 2 is excellent in low-temperature impact resistance, electrical properties and did not occur stress whitening phenomenon. Comparative Example 3 was confirmed that the impact resistance at low temperature and the rigidity is very high, the flexibility is insufficient, the whitening phenomenon occurs after the stress whitening and orientation crystallization.

In addition, when Example 1, Example 2, and Example 3 were compared, it was confirmed that Example 1 and Example 2 exhibited higher flexural modulus than those of Example 3. This can be confirmed that in the case of Examples 1 and 2, the content of the polypropylene block copolymer occupies a relatively high ratio compared to the content of ethylene-octene rubber.

Comparing Example 1 and Example 2, it was confirmed that the AC breakdown strength of Example 1 is superior even though the content of both polypropylene block copolymer and ethylene-octene rubber is similar. This was confirmed that the cause of Example 1 is less contained in the ionic inorganic content.

That is, as the insulating layer of the power cable, it is preferable to use a mixture of polypropylene block copolymer and ethylene-octene rubber as in Examples 1 to 3, wherein the polypropylene block copolymer and ethylene-octene rubber It was confirmed that mixing the content of ionic minerals contained in these 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 polypropylene block copolymer and the ethylene-octene rubber, which are the 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-crosslinkable. Eco-friendly power cable can be provided. In addition, by controlling the crystal size of the insulator polymer resin containing these polypropylene block copolymers and ethylene-octene rubber, it is possible to improve light transmittance to reduce the whitening phenomenon.

100: power cable 110: conductor
120: inner semiconducting layer 130: insulating layer
140: outer semiconducting layer 150: neutral watertight layer
160: outer layer 170: neutral wire

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 having a semiconductivity capable of being expanded by absorbing moisture; And
It includes; outer shell layer surrounding the neutral watertight layer;
The insulating layer includes 30 parts by weight to 80 parts by weight of polypropylene block copolymer and 20 parts by weight to 70 parts by weight of ethylene-octene rubber, based on 100 parts by weight of the polypropylene block copolymer and the ethylene-octene rubber.
The polypropylene block copolymer comprises an ethylene-propylene random block copolymer polymerized from 80 parts by weight to 95 parts by weight of ethylene-propylene random copolymer and 5 parts by weight to 20 parts by weight of ethylene-propylene rubber,
The ethylene-octene rubber is a copolymer of ethylene monomer and 1-octene comonomer, the content of 1-octene comonomer in the ethylene-octene rubber is 5% to 40% by weight, ASTM D 1238 (230 ° C., 2.16kg), the melt index (MI) measured under 6g / 10min,
The insulation layer is a power cable, characterized in that the total transmittance is more than 80%,
The power cable has a tensile strength of 2.4 to 2.7 kg / mm ² and an elongation of 735 to 760% at a tensile rate of 25 mm / min at room temperature in accordance with the IEC-60811-501 standard. Power cable characterized in that the tensile strength of 2.5 ~ 2.8 kg / mm ² and elongation of 650 ~ 680% in minutes.
The power cable of claim 1, wherein the light transmittance is measured according to ASTM D 1003.
The method of claim 1, wherein the insulating layer, the insulating layer further comprises an ionic inorganic,
Based on 100 parts by weight of the polypropylene block copolymer and ethylene-octene rubber, 55 parts by weight to 65 parts by weight of polypropylene block copolymer, 35 parts by weight to 45 parts by weight of ethylene-octene rubber and 0.03 part by weight of ionic inorganic material Power cable to include below.
delete The method of claim 1, wherein the ethylene content in the ethylene-propylene random copolymer is 0.5% to 10% by weight, the ethylene content in the ethylene-propylene rubber is 20% to 60% by weight,
The intrinsic viscosity ratio of the solvent extract of ethylene-propylene rubber (xylene is a solvent) to the intrinsic viscosity of the ethylene-propylene random copolymer is 0.5 to 1.1.
The method according to claim 1, wherein the polypropylene block copolymer has a melt index (MI) measured in accordance with ASTM D 1238 (230 ℃, 2.16kg) 1g / 10min to 10g / 10min, measured according to ASTM D 1003 Cable with less than 5% blur.
The method of claim 1, wherein the polypropylene block copolymer,
A power cable comprising a form in which ethylene-propylene rubber having a size of 0.4 μm or less is dispersed in a matrix including an ethylene-propylene random block copolymer.
According to claim 1, wherein the polypropylene block copolymer has a flexural modulus measured in accordance with the ASTM D790 standard 7000kg / ㎠ to 10000kg / ㎠, heat deformation temperature measured according to the ASTM D648 standard is 90 ℃ to 105 ℃ And a melting point of 154 ° C to 156 ° C.
The polypropylene block copolymer according to claim 1, wherein the polypropylene block copolymer has a Rockwell hardness of 55 to 63 and a notched Izod impact strength of 10 kg · cm / cm to 20 kg · cm / cm measured according to ASTM D256 standard. Power cable.
delete The power cable of claim 1, wherein a melting point of the insulating layer is 140 ° C. to 160 ° C., and a flexural modulus measured according to ASTM D790 is 2000 kg / cm 2 to 4000 kg / cm 2.
The power cable of claim 1, wherein one or more neutral wires are provided between the outer skin layer and the neutral watertight layer.
The power cable of claim 1, wherein the inner semiconducting layer and the outer semiconducting layer each include a thermoplastic resin composition including 20 wt% to 40 wt% of carbon black.
The power cable of claim 1, wherein the shell layer comprises polyethylene and has a melting temperature of 110 ° C. to 130 ° C. 7.

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