KR102018922B1

KR102018922B1 - Power cable

Info

Publication number: KR102018922B1
Application number: KR1020130045408A
Authority: KR
Inventors: 유익현; 남진호; 김웅; 조호숙
Original assignee: 한국전력공사; 엘에스전선 주식회사
Priority date: 2013-04-24
Filing date: 2013-04-24
Publication date: 2019-09-05
Also published as: KR20140126993A

Abstract

The present invention relates to a power cable. Specifically, the present invention relates to a power cable comprising an inner semiconducting layer manufactured from a semiconducting composition that is environmentally friendly and has improved aging characteristics.

Description

Power cable

A general high voltage or ultra high voltage power cable may be formed of an inner semiconducting layer, an insulating layer, an outer semiconducting layer, a sheath layer and the like around the conductor. In particular, the inner semiconducting layer improves the interfacial roughness between the conductor and the insulating layer during cable manufacture, forms a gradient of insulation resistance, and performs a very important function in terms of enhancing the electrical characteristics of the cable.

Recently, as the continuous use temperature of the internal semiconducting layer constituting the high voltage cable has been improved from 90 ° C to 110 ° C, there is a need for a semiconductive material for manufacturing the internal semiconducting layer having improved aging characteristics at a higher temperature. It became. Conventionally, what bridge | crosslinked the thing which mixed polyolefin, such as polyethylene, and carbon black which is a conductive inorganic particle as a base resin which comprises a 90 degreeC semiconducting material has been used normally. However, the crosslinked polyethylene, which has been used as the base resin constituting the semiconductive material, has a disadvantage in that it is not environmentally friendly, such as being difficult to recycle because of its crosslinked form.

On the other hand, the melting point of the polymer itself is 160 ℃ or more, a technique using an environmentally friendly polypropylene as a base resin that can improve the continuous use temperature of the inner semiconducting layer to 110 ℃ class without crosslinking. However, the internal semiconducting layer cannot avoid contact with the metallic material constituting the conductor for the purpose of use, and unlike the polyethylene, the polypropylene contains a large amount of tertiary carbon in the polymer main chain. The problem of deterioration was found to be a very fatal drawback.

Accordingly, in power cables, there is a demand for a power cable including an environmentally-friendly semiconductive material and a semiconducting layer manufactured therefrom while improving aging characteristics such as deterioration or minimization of contact with the metallic material constituting the conductor. It is becoming.

It is an object of the present invention to provide a power cable comprising an internal semiconducting layer made from a semiconducting composition which is capable of improving the aging characteristics to improve the continuous use temperature of the cable.

It is also an object of the present invention to provide a power cable comprising an internal semiconducting layer made from a semiconducting composition which can not cause or minimize deterioration by contact with the metallic material constituting the conductor.

In addition, an object of the present invention is to provide a power cable comprising an inner semiconducting layer that is recyclable and manufactured from an environmentally friendly semiconducting composition.

In order to solve the above problems, the present invention,

A power cable comprising at least one conductor, an inner semiconducting layer surrounding each conductor, an insulating layer surrounding the inner semiconducting layer, an outer semiconducting layer surrounding the insulating layer, and a sheath layer surrounding the outer semiconducting layer, wherein the inner The semiconducting layer is a semiconducting composition comprising a base resin comprising an uncrosslinked polypropylene homopolymer or copolymer, 30 to 70 parts by weight of conductive particles and 0.1 to 5 parts by weight of a metal inactive additive, based on 100 parts by weight of the base resin. An electric power cable, characterized in that formed from.

Here, the metal inactive additive provides a power cable, characterized in that it has a molecular structure of the chelate ligand (chelate legand) form two or more coordination bonds with one metal atom.

In addition, the metal inactive additive has at least two Lewis-base sites (electron donor) in the molecular structure, the Lewis base is characterized in that the amine group, amide group or carboxyl group To provide a power cable.

In addition, the metal inactive additives are N, N'-bis (salicylidene) -1,2-propanediamine, 1,2-bis (3,5-di-t-butyl-4-hydroxycinnamoyl) hydrazine Or N, N'-1,2-ethane diylbis- (N- (carboxymethyl) glycine).

On the other hand, it characterized in that the solubility of the metal-inert additive in paraffin oil at 20 ℃ 0.01g / 100ml or less, it provides a power cable.

In addition, the conductive particles are characterized in that the carbon black, graphite or graphene particles, it provides a power cable.

Furthermore, the semiconductive composition further comprises 0.2 to 3 parts by weight of an amine-based, dialkyl ester-based, thioester-based or phenol-based antioxidant based on 100 parts by weight of the base resin. to provide.

The power cable according to the present invention uses a polypropylene-based resin having a high melting point as the base resin constituting the semiconductive layer, thereby improving the aging characteristics at a higher temperature, thereby exhibiting an excellent effect of improving the continuous use temperature.

In addition, the power cable according to the present invention exhibits an excellent effect of preventing or minimizing deterioration due to contact with the metallic material constituting the conductor, since the semiconductive layer contains a metal inactive additive.

In addition, the power cable according to the present invention exhibits an excellent environmentally friendly effect, such as recycling, by using a non-crosslinked polypropylene resin as the base resin constituting the semiconductive layer.

1 is a cross-sectional view schematically showing the cross-sectional structure of a power cable according to the present invention.
2 is a longitudinal sectional view schematically showing a cross-sectional structure of a power cable according to the present invention.

1 and 2 show an embodiment of a power cable according to the invention.

1 and 2, the power cable according to the present invention is a conductor (1) made of a conductive material such as copper, aluminum, an insulating layer (3) made of an insulating polymer, the conductor (1) and the insulating layer Located between (3) to suppress partial discharge at the interface with the conductor (1), to eliminate the air layer between the conductor (1) and the insulating layer (3), to mitigate local electric field concentration, etc. It may include an inner semiconducting layer (2) to play a role, an outer semiconducting layer (4) to play a shielding role of the cable and an even electric field to the insulator, a sheath layer (5) to protect the cable, and the like. have.

Standards of the conductor 1, the insulating layer 3, the semiconducting layers 2 and 4, the sheath layer 5, and the like may vary according to the use of the cable, the transmission voltage, and the like. The materials constituting the entire layers 2 and 4 and the sheath layer 5 may be the same or different.

The semiconducting composition for forming the inner semiconducting layer 2 of the power cable according to the invention may comprise a non-crosslinked polypropylene resin as the base resin.

By polymer constituting the non-crosslinked polypropylene resin is meant a polymer comprising at least 50% by weight or more of polypropylene, propylene homopolymer and / or propylene and ethylene or α-olefin having 4 to 12 carbon atoms, for example 1 Copolymers with comonomers selected from -butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, and combinations thereof. .

The content of the comonomer may be 15 mol% or less, preferably 10 mol% or less, based on the total moles of monomers constituting the propylene copolymer. In particular, propylene / ethylene copolymers are preferred. In addition, the propylene copolymer may be a random copolymer or a block copolymer in which propylene and ethylene and / or α-olefins are polymerized without regularity. In addition, the polypropylene may include a mixture with polyolefin such as low density polyethylene and linear low density polyethylene.

The propylene homopolymer or copolymer preferably has a maximum crystallization temperature of 110 to 125 ° C. (measured by differential scanning calorimetry (DSC)). When the highest crystallization temperature is less than 110 ° C, the polypropylene homopolymer and / or copolymer is melted under the aging test condition (135 or 150 ° C) required by the IEC International Standard to 110 ° C, which is the continuous use temperature of the cable. If the maximum crystallization temperature exceeds 125 ℃ can be a problem that the crystallization rate during the cooling is faster and the tensile elongation at room temperature is lowered.

In addition, the propylene homopolymer or copolymer preferably has a weight average molecular weight (Mw) of 200,000 to 450,000. When the weight average molecular weight (Mw) is less than 200,000, mechanical properties before and after heating may be lowered, and if it is more than 450,000, workability may be lowered due to high viscosity.

Furthermore, the propylene homopolymer or copolymer preferably has a molecular weight distribution (Mw / Mn) of 2 to 8. When the molecular weight distribution (Mw / Mn) is less than 2, the workability may be lowered due to the high viscosity, and if it is more than 8, the mechanical properties before and after heating may be lowered.

Meanwhile, the propylene homopolymer or copolymer has a melt index of 0.01 to 1000 dg / min (measured by ASTM D-1238) and a melting point (Tm) of 140 to 175 ° C (differential scanning calorimetry (DSC)). Melt enthalpy of 30 to 85 J / g (measured by DSC), flexural modulus at room temperature of 30 to 1400 MPa, more preferably 60 to 1000 MPa (measured according to ASTM D790-00). Can be.

As described above, in the present invention, the propylene homopolymer or copolymer has a high melting point, thereby improving improved aging characteristics at higher temperatures of the inner semiconducting layer 2 made from the propylene homopolymer or copolymer. As a result, it is possible not only to provide a power cable having an improved continuous use temperature, but also to be recycled since it is a non-crosslinked form.

On the other hand, unlike the non-crosslinked propylene homopolymer or copolymer, which is a semiconductive composition based resin for forming the inner semiconductive layer 2 of the power cable according to the present invention, the conventional crosslinked polymer is difficult to recycle and is not environmentally friendly. However, if crosslinking or scorch occurs early in the manufacture of the semiconducting layer 2, it may cause long-term extrudability, such as not being able to exhibit uniform production capacity.

The semiconducting composition forming the inner semiconducting layer 2 of the power cable according to the invention comprises conductive particles to control the electrical conductivity of the inner semiconducting layer 2. There is no particular limitation on the conductive particles, and for example, carbon black such as furnace black, acetylene black, or the like, or graphite, graphene or the like may be used.

The conductive particles such as carbon black are not particularly limited in shape, and may be, for example, spherical, plate-shaped, rod-shaped, or tubular. In addition, the surface area of the conductive particles may be 20 m 2 / g or more, for example, 40 to 1,200 m 2 / g, and preferably, the volume resistance of the expandable polymeric material may be less than 500 Ωm, more preferably less than 20 Ωm. have. In particular, the conductive particles content such as carbon black may be 30 to 70 parts by weight based on 100 parts by weight of the base resin. When the conductive particle content, such as carbon black, is less than 30 parts by weight, it may be difficult to implement the desired semiconducting properties, and when it is more than 70 parts by weight, extrusion may be disadvantageous.

The semiconducting composition for forming the inner semiconducting layer 2 of the power cable according to the present invention is a metal inert additive which is an additive for deactivating the metallic material flowing from the conductor 1 of the power cable to the inner semiconducting layer 2. Include. In the case of the metallic material, for example, transition metal ion atoms such as copper ions, due to the relatively large atomic radius, an additional coordinate bond may be formed in addition to the ionic bond by a given ion order. In order to deactivate the transition metal ion, an additive having a molecular structure in the form of a chelate legand forming two or more coordination bonds with one metal atom is preferable.

The metal inactive additive preferably has at least two Lewis-base sites serving as electron donors in the molecular structure, and the Lewis bases preferably have functional groups such as amines, amides, and carboxyls. Do.

In addition, it is preferable that the metal inactive additive has a solubility in insulating oil such as paraffin oil of 0.01 g / 100 ml (gram of solute dissolved in 100 ml of solvent at 20 ° C) or less. When using a paraffinic insulating oil in the insulating layer (3) in contact with the inner semiconducting layer (2) containing the metal inactive additive in the power cable, if the solubility of the metal inactive additive in the paraffinic insulating oil is large, Since the metal inactive additive may be eluted outwards or transferred to the insulating layer 3, it may be difficult to realize the original characteristics of the metal inactive additive.

In this regard, the metal inactive activator may be preferably a compound of Formulas 1 to 3 below. The compound of formula 1 is N, N'-bis (salicylidene) -1,2-propanediamine (N, N'-bis (salicylidene) -1,2-propanediamine), the compound of formula 2 is 1, 2-bis (3,5-di-t-butyl-4-hydroxycinnamoyl) hydrazine (1,2-bis (3,5-di-tert-butyl-4-hydroxycinnamoyl) hydrazine) of Formula 3 The compound is N, N'-1,2-ethane diylbis- (N- (carboxymethyl) glycine) (N, N'-1,2-ethane diylbis- (N- (carboxymethyl) glycine).

The metal inactive additive may be 0.1 to 5 parts by weight based on 100 parts by weight of the base resin. When the content of the metal inactive additive is less than 0.1 parts by weight, the desired effect, that is, the anti-deterioration effect of the internal semiconducting layer 2 due to deactivation of the metal material flowing from the conductor 1 cannot be achieved, and more than 5 parts by weight. In the case of bleaching may occur due to compatibility problems with the base resin after extrusion.

The semiconducting composition for forming the inner semiconducting layer 2 of the power cable according to the present invention may further include other additives such as antioxidants, lubricants, etc. in addition to the base resin, conductive particles, and metal inactive additives. The antioxidant may be an amine, dialkyl ester, thioester, phenol-based antioxidant, and the like, for example, [3- [3- (3,5-di-t-butyl-4-hydroxy Oxyphenyl) propanoyloxy] -2,2-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propanoyloxymethyl] propyl], 3- (3,5- Di-tert-butyl-4-hydroxyphenyl) propanoate, thiodiethylene bis (3,5-di-tert-butyl-4-hydroxyhydrocinnamate), 3,5-bis (1,1- Dimethylethyl) -4-hydroxybenzenepropionic acid octadecyl ester, propionic acid, 3,3'thiobis-1,1 'dioctadecyl ester, and the like. In addition, the lubricant may be, for example, a polypropylene wax or polyethylene wax having a number average molecular weight (Mn) of 1,000 to 10,000.

The content of each of the other additives such as the antioxidant and the lubricant may be 0.2 to 3 parts by weight based on 100 parts by weight of the base resin.

EXAMPLE

Hereinafter, preferred embodiments of the present invention will be described in detail. However, the invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosure may be made thorough and complete, and to fully convey the spirit of the present invention to those skilled in the art.

After preparing a semiconducting composition with the components and contents shown in Table 1 below, extrusion coating each of the semiconducting compositions melted on a copper conductor of a certain standard, and then adding an insulating composition containing paraffin oil to the polypropylene resin as insulating oil The cable specimens of Example 1 and Comparative Examples 1 and 2 were produced by extrusion coating, respectively. Here, the unit of component content is parts by weight.

Ingredient Example 1 Comparative Example 1 Comparative Example 2 Base material resin 100 100 100 Conductive particles 55 55 55 Metal inactive additives1 0.3 - - Metal Inert Additives2 - - 0.3 Antioxidants 1 0.5 0.5 0.5 Antioxidants 2 0.3 0.3 0.3 Lubricant One One One

Base resin: Polypropylene copolymer (Manufacturer: Basell; Product name: CA-7441)

Conductive particles: Carbon black (acetylene black)

Metal inactive additive 1: 1,2-bis (3,5-di-t-butyl-4-hydroxycinnamoyl) hydrazine (manufacturer: Basf; product name: IR-MD1024; solubility in paraffin oil: 0.01 g / 100 ml (20 ° C))

Metal inactive additive 2: stearyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate (manufacturer: BASF); product name: IR-1076; solubility in paraffin oils : 31 g / 100 ml (20 ° C))

Antioxidant 1: Ciba IR-1035

Antioxidant 2: Ciba PS-802

Lubricant: Polypropylene wax with a number average molecular weight of 7,000 (manufacturer: Mitsui Kical; Product Name: NP056)

The cable specimens of Example 1 and Comparative Examples 1 and 2 were measured for tensile strength and elongation at a tensile rate of 250 mm / min in accordance with IEC 60811-1-1, respectively, and were subjected to mechanical properties after heat aging at 150 ° C. for 168 hours. The change was measured and the results are shown in Table 2 below.

Properties Example 1 Comparative Example 1 Comparative Example 2 Tensile strength (kgf / ㎡) 1.45 1.44 1.44 Elongation (%) 550 550 550 Tensile strength residual after aging (%) 95 132 117 Elongation Remaining Rate after Aging (%) 90 45 60

As shown in Table 2, the cable specimen of Example 1 including the specific metal inactive additive according to the present invention in the inner semiconducting layer, the tensile strength residual ratio and elongation residual ratio after aging is 95% and 90%, respectively, Since the aging characteristics of the semiconducting layer were not less than 75%, the aging characteristics of the semiconducting layer were remarkably improved, whereas the cable specimen of Comparative Example 1 which did not include the metal inactive additive in the inner semiconducting layer had a tensile strength due to deterioration of the inner semiconducting layer after aging. Increasingly, the mechanical properties were markedly deteriorated such that the elongation was not much lower than the standard 75%.

In addition, the cable specimen of Comparative Example 2 comprising an additive having a solubility in paraffin oil of 31 g / 100 ml (20 ° C.) as another metal inactive additive other than the specific metal inactive additive according to the present invention in the inner semiconducting layer has an inner portion thereof. The metal inactive additive contained in the semiconducting layer is eluted and carried out in paraffin oil impregnated in the insulating layer in contact with the inner semiconducting layer, thereby failing to realize the characteristics of the original metal inactive additive, so that tensile strength is increased and elongation is a reference value. It was confirmed that the mechanical properties were reduced, such as less than 75%.

Although the present specification has been described with reference to preferred embodiments of the invention, those skilled in the art may variously modify and change the invention without departing from the spirit and scope of the invention as set forth in the claims set forth below. It could be done. Therefore, it should be seen that all modifications included in the technical scope of the present invention are basically included in the scope of the claims of the present invention.

1: conductor 2: inner semiconducting layer
3: insulation layer 4: outer semiconducting layer
5: sheath layer

Claims

A power cable comprising at least one conductor, an inner semiconducting layer surrounding each conductor, an insulating layer surrounding the inner semiconducting layer, an outer semiconducting layer surrounding the insulating layer, and a sheath layer surrounding the outer semiconducting layer,
The inner semiconducting layer may be a base resin including a non-crosslinked polypropylene homopolymer or copolymer, a half including 30 to 70 parts by weight of conductive particles and 0.1 to 5 parts by weight of a metal inactive additive, based on 100 parts by weight of the base resin. Formed from a conductive composition,
The metal inactive additive has a molecular structure in the form of a chelate ligand (chelate legand) forming two or more coordination bonds with one metal atom, and Lewis-base that serves as an electron donor in the molecular structure. and at least two sites, wherein said Lewis base comprises at least one member selected from the group consisting of amine groups, amide groups and carboxyl groups.

delete

The method of claim 1,
The metal inactive additive may be N, N'-bis (salicylidene) -1,2-propanediamine, 1,2-bis (3,5-di-t-butyl-4-hydroxycinnamoyl) hydrazine or N And N'-1,2-ethane diylbis- (N- (carboxymethyl) glycine).

The method according to claim 1 or 4,
A power cable, characterized in that the solubility at 20 ° C. of paraffin oil of the metal inactive additive is 0.01 g / 100 ml or less.

The method according to claim 1 or 4,
The conductive particles are carbon black, graphite or graphene particles, characterized in that the power cable.

The method according to claim 1 or 4,
The semiconductive composition further comprises 0.2 to 3 parts by weight of an amine-based, dialkyl ester-based, thioester-based or phenol-based antioxidant based on 100 parts by weight of the base resin.

A base resin including an uncrosslinked polypropylene homopolymer or copolymer, 30 to 70 parts by weight of conductive particles and 0.1 to 5 parts by weight of a metal inactive additive, based on 100 parts by weight of the base resin,
The metal inactive additive has a molecular structure in the form of a chelate ligand (chelate legand) forming two or more coordination bonds with one metal atom, and Lewis-base that serves as an electron donor in the molecular structure. and at least two sites, wherein the Lewis base is an amine group, an amide group or a carboxyl group.

The method of claim 8,
The metal inactive additive may be N, N'-bis (salicylidene) -1,2-propanediamine, 1,2-bis (3,5-di-t-butyl-4-hydroxycinnamoyl) hydrazine or N , N'-1,2-ethane diylbis- (N- (carboxymethyl) glycine), a semiconducting composition.

The method according to claim 8 or 9,
A semiconducting composition, characterized in that the solubility of the metal-inert additive in paraffin oil at 20 ° C. is 0.01 g / 100 ml or less.