KR20170004643A - Power cable - Google Patents

Abstract

The present invention relates to a power cable, and more particularly to the power cable which is lightweight, has excellent corrosion resistance, and has a watertight layer of which interlayer adhesiveness is maintained despite external physical impact and changes in temperature and of which detachment is efficiently inhibited.

Description

Power cable {Power cable}

The present invention relates to power cables. Specifically, the present invention relates to a power cable having a watertight layer that is lightweight compared to a conventional power cable, is excellent in corrosion resistance, and is effectively prevented from peeling due to an interlayer adhesive force being maintained even under external physical impact and temperature changes.

Power cables, such as submarine cables and underground cables, generally include a watertight layer that inhibits the penetration of moisture from the outside.

1 schematically shows a cross-sectional structure of a power cable disclosed in U.S. Patent No. 4,472,597. 1, the conventional power cable includes a conductor 1, an inner semiconductive layer 2, an insulating layer 3, an outer semiconductive layer 4, a metal shielding layer 5, a conductive tape layer 8, The watertight layer 7, and the outer jacket 6 in this order.

When aluminum laminated tape coated with polyethylene on both sides of an aluminum foil is used as the watertight layer 7, the aluminum foil is vulnerable to corrosion, Damage can shorten the life of the cable.

2 schematically shows a cross-sectional structure of a power cable disclosed in U.S. Patent No. 4,501,928. As shown in FIG. 2, the conventional power cable includes a conductor 1 ', an inner semiconductive layer 2', an insulating layer 3 ', an outer semiconductive layer 4', a metal shielding layer 5 ' The conductive tape 6 ', the watertight layer 7', and the outer jacket 8 'in this order.

When a lead laminate tape coated with polyethylene or polyvinyl chloride on both surfaces of a lead foil is used as the watertight layer 7 ', the weight of the lead foil is low and the lightness of the cable is deteriorated .

In addition, the watertight layer 7, 7 'applied to the conventional power cable is insufficiently adhered to the outer jacket 6, 8' so that the watertight layer 7, 7 ' And the outer jacket 6 and 8 'are peeled from each other.

On the other hand, the electric power cables disclosed in Japanese Laid-Open Patent Publications Nos. 1994-309948, 2001-023453 and 2014-032912, and US Patent Application Publication No. 2002-0080213 are used to improve the adhesion between the watertight layer and the outer jacket The adhesive layer or the adhesion-assisting layer may be formed of a metal layer and an adhesion-assisting layer coated on the surface of the metal layer. However, the adhesion force of the adhesive layer or the adhesion- And there is a problem that the adhesive force and the peeling force remarkably deteriorate due to the external physical impact.

Accordingly, a power cable having a watertight layer, which is lighter in weight than conventional power cables, has improved corrosion resistance, and is effectively prevented from peeling by maintaining the interlaminar adhesion even under external physical impact and temperature changes, is in desperate need.

It is an object of the present invention to provide a power cable which is lighter than conventional power cables.

Another object of the present invention is to provide a power cable having a watertight layer in which the corrosion resistance is improved and the interlaminar adhesive force is maintained even when the external physical impact and the temperature are changed, whereby the peeling is effectively suppressed.

In order to solve the above problems,

A semiconductor device comprising: a core conductor; an inner semiconductive layer surrounding the central conductor; an insulating layer surrounding the inner semiconductive layer; an outer semiconductive layer surrounding the insulating layer; a metal shielding layer surrounding the outer semiconductive layer; A buffer layer surrounding the watertight layer, an adhesive layer surrounding the buffer layer, and an outer jacket surrounding the adhesive layer, wherein the buffer layer comprises a soft resin relative to the adhesive layer, the resin comprising a resin contained in the watertight layer, Which is easy to adhere and compatible with a resin contained in the power cable.

Wherein the buffer layer comprises a resin having a melting point of 80 ° C or more, a density of 0.85 to 0.94, and a shore A of 65 or more.

In addition, the buffer layer includes at least one ethylene copolymer selected from the group consisting of ethylene butyl acrylate (EBA), ethylene vinyl acetate (EVA), and ethylene acrylic acid (EAA).

The thickness of the buffer layer is 1 to 3 mm.

Further, the thickness of the adhesive layer is 4 to 6 mm.

The waterproof layer includes a copper tape and an adhesive auxiliary layer formed on the copper tape, and the adhesive layer is formed by immersing the power cable in distilled water at a temperature of 80 DEG C for 7 days, Wherein the adhesive layer comprises a resin having a density of 0.90 or more and a degree of crystallinity of more than 50% and not including an additive that forms a moisture transfer path, wherein the adhesive layer has an adhesive strength of not less than 70% .

Here, the adhesive layer includes a resin having a degree of crystallinity of 60% or more.

The adhesive for forming the adhesion-assisting layer may further comprise a copolymer of an olefin and a polar monomer or a blend resin.

The polar monomer may be a vinyl ester monomer of vinyl acetate or vinyl versatate, a vinyl-unsaturated carboxylic acid monomer of methacrylic acid, acrylic acid, maleic acid or itaconic acid, an acrylic monomer of (meth) acrylate or alkyl (meth) And a power cable.

Further, the content of the polar monomer is 5 to 25% by weight based on the total weight of the random copolymer resin.

Here, the random copolymer resin of the olefin and the polar monomer is ethylene acrylic acid (EAA), ethylene vinyl acetate (EVA), or ethylene butyl acrylate (EBA).

On the other hand, the power cable is characterized in that the adhesive layer comprises a high density polyethylene (HDPE) resin.

Here, the thickness of the copper tape is 0.05 to 0.38 mm, and the thickness of the adhesion-assisting layer is 0.05 to 0.1 mm.

Also, the outer jacket comprises a high density polyethylene (HDPE) resin, and the thickness is 0.1 to 8 mm.

The metal shield layer may include a first semi-conductive tape layer transversely disposed on the outer semiconductive layer, a metal layer disposed on the first semi-conductive tape layer and including a plurality of copper neutral lines, and a second semi- And a tape layer.

Further, the power cable is characterized in that the insulating layer is made of crosslinked polyethylene (XLPE).

On the other hand, the watertight layer has both ends overlapped with each other, and the lower surface and the upper surface of the watertight layer in the overlapping region are bonded by a hot melt adhesive.

Wherein the hot melt adhesive is made of polyamide, polyethylene vinyl acetate or a rubber based resin having a creep resistance temperature and a softening temperature of at least 80 ° C.

On the other hand, a power cable is provided, wherein the inner semiconductive layer, the insulating layer and the outer semiconductive layer are made of a base resin of a similar type.

The power cable according to the present invention includes a watertight layer made of a lightweight material, so that the power cable has a lightweight effect compared to the conventional power cable.

The power cable according to the present invention includes a watertight layer made of a material excellent in corrosion resistance, so that corrosion of the watertight layer is suppressed.

The power cable according to the present invention can improve the adhesive force between the watertight layer and the outer jacket and effectively prevent moisture penetration which is a main cause of lowering the adhesion strength between the watertight layer and the outer jacket, By additionally containing a buffer layer for buffering, peeling of the watertight layer can be effectively suppressed even with external physical impact and temperature change, resulting in an excellent effect of maintaining the function of the watertight layer and shortening the life of the cable.

1 schematically shows a cross-sectional structure of a conventional power cable.
2 schematically shows a cross-sectional structure of another conventional power cable.
3 is a cross-sectional view schematically showing a cross-sectional structure of an embodiment of a power cable according to the present invention.
4 is a longitudinal sectional view schematically showing a cross-sectional structure of an embodiment of a power cable according to the present invention.
5 schematically shows a cross-sectional structure of a watertight layer 70 in a power cable according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. Like reference numerals designate like elements throughout the specification.

3 and 4 schematically show a cross-sectional structure of an embodiment of a power cable according to the present invention. 3 and 4, the power cable according to the present invention includes a center conductor 10, an inner semiconductive layer 20 surrounding the central conductor 10, an insulating layer (not shown) surrounding the inner semiconductive layer 20 A first semi-conductive tape layer 51, a metal layer 60 and a second semi-conductive tape layer 52 surrounding the outer semiconductive layer 40. The first semi- A watertight layer 70 surrounding the metal shield layer, a watertight layer 70 that protects the watertight layer 70 from an external impact on the cable, and the watertight layer 70, when the external impact is applied, A buffer layer 80 for maintaining the adhesion of the adhesive layer 90 to the adhesive layer 90 and an adhesive layer 90 for bonding the waterproof layer 70 to the outer jacket 100 and an outer jacket 100.

The center conductor 10 may be formed of a single wire made of copper, aluminum, preferably copper, or a twisted wire associated with a plurality of wires. The diameter of the center conductor 10, the diameter of the wire constituting the twisted wire, The standard to be included may vary depending on the transmission voltage of the power cable, the use thereof, etc., and may be appropriately selected by a person skilled in the art. For example, when the power cable according to the present invention is used as a submarine cable for installation, flexibility, or the like, the center conductor 10 is preferably formed by a twisted wire excellent in flexibility than a wire.

The inner semiconductive layer 20 is disposed between the central conductor 10 and the insulating layer 30 to remove an air layer inducing interlayer delamination between the center conductor 10 and the insulating layer 30, And relaxes the electric field concentration. On the other hand, the outer semiconductive layer 40 functions to uniformly apply an electric field to the insulating layer 30, to alleviate local field concentration, and to protect the cable insulation layer from the outside.

Generally, the inner semiconductive layer 20 and the outer semiconductive layer 40 are formed by dispersing conductive particles such as carbon black, carbon nanotube, carbon nanoplate, and graphite in a base resin, and a crosslinking agent, an antioxidant, Wherein the base resin is formed by extrusion of a semi-conductive composition which is further added, and the base resin is an insulating composition for forming the insulating layer (30) for the interlayer adhesion between the semiconductive layer (20, 40) It is preferable to use a series of olefin resins similar to the base resin, for example, a copolymer resin of an olefin and an acrylic monomer, particularly ethylene butyl acrylate (EBA), ethylene ethyl acrylate (EEA) and the like.

For example, in the case of a 345 kV power cable, the thickness of the inner semiconductive layer 20 may be 1.0 to 2.5 mm. The thickness of the inner and outer semiconductive layers 20 and 40 may vary depending on the transmission voltage of the cable. And the thickness of the outer semiconductive layer 40 may be 1.0 to 2.5 mm.

The insulating layer 30 may be, for example, a polyolefin resin such as polyethylene, polypropylene or the like as a base resin, and may preferably be formed by extrusion of an insulating composition comprising a polyethylene resin.

The polyethylene resin may be ultra low density polyethylene (ULDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), or a combination thereof. The polyethylene resin may be a homopolymer, a random or block copolymer of ethylene and an? -Olefin such as propylene, 1-butene, 1-pentene, 1-hexene or 1-octene, or a combination thereof.

The insulating layer 30 may include a crosslinking agent. The insulating layer 30 may be formed of a crosslinked polyolefin (XLPO), preferably a crosslinked polyethylene (XLPE) ). The insulating composition may further include other additives such as an antioxidant, an extrusion-promoting agent, and a crosslinking assistant.

The crosslinking agent may be a silane crosslinking agent or a crosslinking agent such as dicumylperoxide, benzoylperoxide, laurylperoxide, t-butylcumylperoxide, di (t-butylperoxyisopropyl) benzene, -Dimethyl-2,5-di (t-butylperoxy) hexane, di-t-butyl peroxide and the like. The crosslinking agent may be included in an amount of 1 to 5 parts by weight based on 100 parts by weight of the base resin.

The thickness of the insulating layer 30 may differ depending on the transmission voltage of the power cable. For example, in the case of a 345 kV power cable, the thickness of the insulating layer 30 may be 23.0 to 31.0 mm.

The metal shield layer is formed of a semi-conductive tape layer 50 formed on each of upper and lower portions of a metal layer 60 formed by a plurality of neutral lines made of metal, preferably copper, 51 and the second semi-conductive tape layer 52 can be formed. The second semi-conductive tape layer 52 protects the cable under harsh environmental conditions such as seabed and serves as a path for allowing the fault current to escape to the outside through the ground .

The first semi-conductive tape layer (51) performs buffering to suppress deformation of the insulating layer (30) due to the load of the metal layer (60) (60). In addition, the first and second semi-conductive tape layers 51 and 52 may be a wet-swellable tape, and in this case, a water-shielding function for blocking moisture may be performed in parallel. The thickness of the semi-conductive tape forming the first and second semi-conductive tape layers 51 and 52 may be, for example, about 200 to 1,000 μm.

The thickness of the metal layer 60 forming the metal shield layer may be, for example, about 1.0 to 3.0 mm, the thickness of the first semi-conductive tape layer 51 is 0.2 to 1.0 mm, The thickness of the tape layer 52 may be 0.85 to 0.95 mm.

5 schematically shows a cross-sectional structure of a watertight layer 70 in a power cable according to the present invention. As shown in FIG. 5, the watertight layer 70 may comprise a metal, preferably a copper tape 71 and an adhesion-promoting layer 72. The water-tight layer (70) functions to prevent moisture penetrated through the outer jacket (100) from penetrating into the insulating layer (30).

The thickness of the copper tape 71 may be, for example, about 0.05 to 0.38 mm, and the thickness of the adhesion-assisting layer 72 may be, for example, about 0.05 to 0.1 mm. The adhesion-promoting layer 72 should be as thin as possible to avoid adverse effects on the electrical properties of the cable.

In the watertight layer, the copper tape 71 is superior in corrosion resistance to the conventional aluminum foil layer, and is advantageous in that it is light in weight compared to the conventional lead foil layer. On the copper tape 71, an adhesion-assisting layer 72 is formed. Since the adhesion of the copper tape 71 and the buffer layer 80 is not easy, an adhesion-assisting layer 72 made of a resin that is easily adhered to the adhesive layer 80 is laminated on the copper tape 71 lamination.

A method of laminating the adhesion-assisting layer 72 is not particularly limited, and for example, deposition, electro deposition, extrusion, etc. may be used. The adhesive layer 72 may be formed on the watertight layer 70 and the outer jacket 100 or between the watertight layer 70 and the buffer layer 80 in a harsh condition in which an impact is applied from outside of the cable, ) And a function of suppressing the corrosion of the copper tape 71. [0064]

The adhesion supporting layer 72 is formed on the outer jacket 100 or the copper tape 71 with respect to the copper tape 71 measured after immersing the power cable in distilled water having a temperature of 80 ° C. for 7 days, And an adhesive having an adhesive force to make the peel force residual rate of the adhesive layer 90 70% or more. The peeling force residual rate refers to the initial value of the peeling force of the outer jacket 100 with respect to the copper tape 71 before immersion of the power cable, 100 "). ≪ / RTI >

If the residual force of the peeling force is less than 70%, the tight adhesion between the watertight layer 70 and the outer jacket 100 can not be maintained under a severe condition that an impact is applied from the outside of the cable or the temperature rapidly changes.

For example, the adhesion-assisting layer 72 may be formed of an acrylic resin, an olefin resin, preferably an adhesive containing a random copolymer resin of an olefin and a polar monomer as a base resin. The adhesion-promoting layer 72 may be formed by a general coating process such as spraying, impregnating, or extruding.

The polar monomers include vinyl ester monomers such as vinyl acetate and vinyl versatate; Vinyl-unsaturated carboxylic acid monomers such as methacrylic acid, acrylic acid, maleic acid and itaconic acid; (Meth) acrylate, alkyl (meth) acrylate and the like, or a combination thereof, and the content of the polar monomer is 5 to 25% by weight, preferably 5 to 25% by weight, To 20% by weight.

Preferably, the base resin of the adhesive forming the adhesion-assisting layer 72 may be ethylene acrylic acid (EAA), ethylene vinyl acetate (EVA), ethylene butyl acrylate (EBA), or the like.

As shown in FIG. 4, the watertight layer 70 may be overlapped at both ends to realize better watertightness, and the lower and upper surfaces of the watertight layer 70 in the overlapping region may be hot melt hot melt adhesive. The hot-melt adhesive is a hot-melt adhesive or a pressure-sensitive adhesive which is applied in a liquid state at a high temperature using a 100% thermoplastic resin without using water or a solvent at all.

The hot-melt adhesive does not require a drying process, such as other solvent-based adhesives, water-dispersed adhesives, and the like, and has a low work space and fast bonding speed. The material of the hot melt adhesive may be, for example, polyurethane, polyamide, polyester, polyethylene vinyl acetate, rubber, and the like, and may further include wax, a pressure sensitive adhesive, a plasticizer, a filler and an antioxidant.

The hotmelt is preferably made of a polyamide or rubber series resin having a creep resistance temperature and a softening temperature of at least 80 DEG C for use in a power cable. For example, Henkel Quot; Q8740 " or " Q6239 "

The buffer layer 80 is disposed between the watertight layer 70 and the adhesive layer 80 to absorb an external impact on the cable to prevent damage to the watertight layer 70, particularly the copper tape 71, And performs a function of suppressing peeling.

Particularly, when the external impact on the cable exceeds the degree that it can be absorbed by the buffer layer 80, a part of the impact is transmitted to the watertight layer 70, particularly the copper tape 71, The buffer layer 80 may have a recessed portion partially formed on the tape 71. The depressed portion may be a passage through which the moisture penetrated from the outside moves in the longitudinal direction of the cable. So as to further prevent the water from moving in the longitudinal direction of the cable.

In the conventional power cable having no buffer layer 80, when the impact is applied from the outside, the impact is transmitted to the watertight layer to cause delamination, and in particular, when a depression is formed in the watertight layer, The depression may be a passage through which moisture penetrated from the outside moves in the longitudinal direction.

The buffer layer 80 preferably includes a resin having a melting point of 80 ° C or more, a density of 0.85 to 0.94, and a shore A of 65 or more so as to withstand the heat generated during operation of the cable. If the density of the resin constituting the buffer layer 80 is less than 0.85 and the shore A is less than 65, the external impact to the cable can not be sufficiently absorbed. On the other hand, if the density is greater than 0.94, The depression that can be formed in the recess 71 can not be sufficiently filled.

Since the buffer layer 80 is disposed between the water-tight layer 70, particularly the adhesion-assisting layer 72 and the adhesive layer 90, the resin contained in the buffer layer 80 is preferably bonded It is preferable that adhesion between the resin contained in the auxiliary layer 72 and the resin contained in the adhesive layer 90 is favorable and compatible.

The resin contained in the buffer layer 80 may be at least one selected from the group consisting of ethylene copolymer, preferably ethylene butyl acrylate (EBA), ethylene vinyl acetate (EVA), ethylene acrylic acid (EAA) And may include copolymers of ethylene and? -Olefins such as 1-butene, 1-hexene and 1-octene, and rubber series.

The thickness of the buffer layer 80 may be 1 to 3 mm. If the thickness of the adhesive layer 90 is less than 1 mm on the assumption that the thickness of the adhesive layer 90 is as described below, the buffer layer 80 absorbs the external impact on the cable and fills the depressed portion of the watertight layer formed by the external impact On the other hand, if the thickness exceeds 3 mm, the outer diameter of the cable may unnecessarily increase.

The adhesive layer 90 functions to adhere the water-tight layer 70 and the buffer layer 80 to the outer jacket 100 and blocks the moisture that has passed through the outer jacket 100, And functions to suppress deterioration of peeling force of the water-tight layer (70) and the adhesive layer (90) with respect to the buffer layer (80).

Here, the adhesive layer 90 may be made of a resin having a density of 0.90 or more, for example, 0.90 to 0.97, a degree of crystallinity of more than 50%, for example, more than 50% but not more than 90%, preferably not less than 60% , Whereby the melting point may be 100 ° C or higher, for example 100 to 140 ° C.

Since the adhesive layer 90 does not add the additive such as carbon black which forms the high density and the high degree of crystallinity and the moisture transfer path unlike the outer jacket 100, water permeability is improved, It is possible to suppress deterioration of the peeling force of the adhesive layer (87) and the adhesive layer (90) with respect to the buffer layer (80).

Further, the thickness of the adhesive layer 90 may be 4 to 6 mm. If the thickness of the adhesive layer 90 is less than 4 mm, the peeling force of the adhesive layer 90 with respect to the watertight layer 70 and the buffer layer 80 is lowered due to moisture penetration, While the overall diameter of the power cable is unnecessarily increased when the thickness of the adhesive layer 90 is greater than 6 mm and is gradually cooled upon cooling after extrusion to form a plurality of neutral wires A protruding shape may appear on the outer jacket 100 surface.

The adhesive layer 90 may be applied to the watertight layer 80, the buffer layer 80 and the outer jacket 100 for close adhesion with the watertight layer 70, the buffer layer 80 and the outer jacket 100. [ For example, an ethylene homopolymer or copolymer, preferably a high density polyethylene (HDPE) resin.

The outer jacket 100 may include polyethylene, polyvinyl chloride, polyurethane, and the like. In order to maintain a close adhesive force with the adhesive layer 90, the outer jacket 100 may be made of a resin similar to the resin constituting the adhesive layer 90, For example, it is preferable that it is made of a polyethylene resin, and since it is disposed at the outermost portion of the cable, it is more preferable that it is made of a high-density polyethylene (HDPE) resin in consideration of mechanical strength. In addition, the outer jacket 100 may contain a small amount of additive such as carbon black, for example, 2 to 3% by weight to realize the hue of the power cable.

The outer jacket 100 preferably has a thickness of, for example, 0.1 to 8 mm in order to primarily absorb the impact when an impact is applied to the cable from the outside and maintain the tight adhesion with the adhesive layer 90 Do.

As described above, the power cable according to the present invention is lightweight compared to conventional power cables by forming the base layer of the watertight layer 70 with a copper tape 71 that is lightweight compared to conventional lead and superior in corrosion resistance compared to conventional aluminum Excellent corrosion resistance.

The buffer layer 80 is disposed between the watertight layer 70 and the adhesive layer 90 so that the buffer layer 80 can be easily adhered to and mixed with a material constituting these layers. The material of the auxiliary layer 72 and the adhesive layer 90 is precisely controlled to maximize the interlaminar adhesive force and to suppress delamination due to moisture penetration and to transmit an external impact to the cable to the watertight layer 70 Thereby preventing the watertight layer 70, particularly the copper tape 71 from being damaged, and furthermore, when a part of the impact on the cable is transmitted to the copper tape 71 to form a partial depression, ) Can fill the depressed portion and prevent moisture from moving along the depressed portion in the longitudinal direction of the cable.

[Example]

1. Manufacturing Example

An adhesive layer (high-density polyethylene having a density of 0.956), a copper tape, and an adhesion-promoting layer (ethylene vinyl acetate: polyethylene terephthalate) at a press temperature of 160 DEG C (10 minutes), a cooling temperature of 40 DEG C (10 minutes) and a pressure of 4,800 kg / ), An adhesive layer (high-density polyethylene having a density of 0.956), and an outer jacket (high-density polyethylene, 2.5 wt% of carbon black) were sequentially laminated. In addition, sample sheets of Examples and Comparative Examples in which litmus paper was inserted between two adhesive layer specimens shown in Table 1 below were prepared.

Suzy Thickness (mm) Example 2 Resin 1 4.0 Example 3 Resin 1 5.0 Comparative Example 1 Resin 1 0.25 Comparative Example 2 Resin 1 0.5 Comparative Example 3 Resin 2 0.25 Comparative Example 4 Resin 2 0.5 Comparative Example 5 Resin 2 4.0 Comparative Example 6 Resin 2 5.0

- Resin 1: High density polyethylene (density 0.956)

- Resin 2: Ethylene / acrylic acid random copolymer resin (density 0.895)

2. Property evaluation

1) Evaluation of peel strength

The peel force of the outer jacket against the copper tape was measured before and after immersing the sample sheet of Example 1 in a basic aqueous solution of pH 8.5 and 80 ° C. The peel strength measurement results are shown in Table 2 below.

Before immersion 7 days after immersion 21 days after flooding 42 days after flooding 84 days after flooding Peel force (N / mm) 0.86 0.80 0.77 0.82 0.99 Peel force residual rate (%) 100 93 89 95 115

As shown in Table 2, the power cable of Example 1 according to the present invention was excellent in water-repellency and adhesiveness of the adhesive layer, so that the interlayer adhesion between the water-tight layer and the outer jacket remained at 70% .

2) Water permeability evaluation

After immersing the specimens of Examples 2 and 3 and Comparative Examples 1 to 6 in a basic aqueous solution of pH 8.5 and 80 ° C, the time until the basic solution passed through the adhesive layer specimen and discolored litmus paper was measured. The evaluation results are shown in Table 3 below.

Time to moisture penetration Example 2 More than 125 days Example 3 More than 125 days Comparative Example 1 7 days Comparative Example 2 48 days Comparative Example 3 0 days Comparative Example 4 3 days Comparative Example 5 12th Comparative Example 6 19th

As shown in Table 3, the adhesive layers of Examples 2 and 3 according to the present invention were formed of a resin having a density of 0.90 or more and had a thickness of a specific value or more, and thus water-repellency was found to be sufficient.

On the other hand, the adhesive layers of Comparative Examples 1 to 4 were found to have insufficient water repellency with a thickness less than the threshold value, and the adhesive layers of Comparative Examples 5 and 6 were found to have insufficient water repellency because the density of the resin constituting them was below the threshold value.

While the present invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims. . It is therefore to be understood that the modified embodiments are included in the technical scope of the present invention if they basically include elements of the claims of the present invention.

10: conductor 20: inner semiconductive layer
30: insulating layer 40: outer semiconductive layer
50: semi-conductive tape layer 60: metal layer
70: watertight layer 80: buffer layer
90: adhesive layer 100: outer jacket

Claims (19)

A semiconductor device comprising: a core conductor; an inner semiconductive layer surrounding the central conductor; an insulating layer surrounding the inner semiconductive layer; an outer semiconductive layer surrounding the insulating layer; a metal shielding layer surrounding the outer semiconductive layer; A buffer layer surrounding the watertight layer, an adhesive layer surrounding the buffer layer, and an outer jacket surrounding the adhesive layer,
Wherein the buffer layer comprises a soft resin as compared to the adhesive layer and the resin is a resin that is easy to adhere and compatible with the resin contained in the watertight layer and the resin contained in the adhesive layer. The method according to claim 1,
Wherein the buffer layer comprises a resin having a melting point of 80 DEG C or higher, a density of 0.85 to 0.94, and a hardness (shore A) of 65 or more. 3. The method of claim 2,
Wherein the buffer layer comprises at least one ethylene copolymer selected from the group consisting of ethylene butyl acrylate (EBA), ethylene vinyl acetate (EVA), and ethylene acrylic acid (EAA). 4. The method according to any one of claims 1 to 3,
Wherein the thickness of the buffer layer is 1 to 3 mm. 5. The method of claim 4,
And the thickness of the adhesive layer is 4 to 6 mm. 4. The method according to any one of claims 1 to 3,
Wherein the watertight layer comprises a copper tape and an adhesion-assisting layer formed on the copper tape, wherein the adhesion-promoting layer is formed by immersing the power cable in distilled water at a temperature of 80 DEG C for 7 days and then peeling off the outer jacket And an adhesive having an adhesive force to make the residual force ratio 70% or more,
Wherein the adhesive layer comprises a resin having a density of at least 0.90 and a degree of crystallinity of more than 50% and not including an additive that forms a moisture transfer path. The method according to claim 6,
Characterized in that the adhesive layer comprises a resin having a degree of crystallinity of at least 60%. The method according to claim 6,
Wherein the adhesive forming the adhesion-promoting layer comprises copolymerization of an olefin and a polar monomer or a blend resin. 9. The method of claim 8,
The polar monomer may be a vinyl ester monomer of vinyl acetate or vinyl versatate, a vinyl-unsaturated carboxylic acid monomer of methacrylic acid, acrylic acid, maleic acid or itaconic acid, or an acrylic monomer of (meth) acrylate or alkyl (meth) acrylate Features, power cable. 9. The method of claim 8,
Wherein the content of the polar monomer is 5 to 25% by weight based on the total weight of the random copolymer resin. 10. The method of claim 9,
Wherein the random copolymer resin of the olefin and the polar monomer is ethylene acrylic acid (EAA), ethylene vinyl acetate (EVA), or ethylene butyl acrylate (EBA). 4. The method according to any one of claims 1 to 3,
Wherein the adhesive layer comprises a high density polyethylene (HDPE) resin. The method according to claim 6,
Wherein the thickness of the copper tape is 0.05 to 0.38 mm and the thickness of the adhesion assisting layer is 0.05 to 0.1 mm. 4. The method according to any one of claims 1 to 3,
Wherein the outer jacket comprises a high density polyethylene (HDPE) resin and the thickness is 0.1 to 8 mm. 4. The method according to any one of claims 1 to 3,
Wherein the metal shielding layer comprises a first semi-conductive tape layer transversely disposed on the outer semiconductive layer, a metal layer disposed on the first semi-conductive tape layer and including a plurality of copper neutral lines, and a second semi- And a power cable. 4. The method according to any one of claims 1 to 3,
Wherein the insulation layer is made of crosslinked polyethylene (XLPE). 4. The method according to any one of claims 1 to 3,
Wherein the watertight layer has both ends superimposed on each other and the lower surface and the upper surface of the watertight layer in the overlap region are bonded by hot melt adhesive. 18. The method of claim 17,
Wherein the hot melt adhesive comprises polyamide, polyethylene vinyl acetate or a rubber based resin having a creep resistance temperature and a softening temperature of at least 80 占 폚. 4. The method according to any one of claims 1 to 3,
Wherein the inner semiconductive layer, the insulating layer and the outer semiconductive layer are made of a base resin of a similar type.

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