KR20170007903A - Power cable - Google Patents

Abstract

The present invention relates to a power cable. More particularly, the present invention relates to a power cable which efficiently suppresses a lamination on an overlap part of both ends of a metal laminate in case of the permeation of water and an external physical impact or temperature change, has a lightweight watertight layer with high corrosion resistance, and is structurally stable by a high interlayer adhesive force. The power cable includes a central conductor, an inner semiconducting layer surrounding the central conductor, an insulation layer surrounding the inner semiconducting layer, an external semiconducting layer surrounding the insulation layer, a metal shield layer surrounding the external semiconducting layer, the watertight layer surrounding the metal shield layer, and an external jacket surrounding the watertight layer.

Description

Power cable {Power cable}

The present invention relates to power cables. Specifically, the present invention has a water-tight layer which is effectively prevented from peeling off the overlapping portions of both ends of the metal laminate even when moisture permeates and changes in external physical impact or temperature, and is lightweight and excellent in corrosion resistance, Structurally stable power cable.

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. 4,501,928. 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 semi- The watertight layer 7, and the outer jacket 8 in this order.

Here, in the case where a metal laminate having polyethylene, polyvinyl chloride, or the like coated on both sides of the metal foil is used as the watertight layer 7, in order to realize better watertightness characteristics as shown in Fig. 1, the amount of the metal laminate The ends are superimposed on each other and a hot melt adhesive can be applied between the overlapped metal laminates.

However, the conventional hot-melt adhesive has a problem in that the adhesive force is insufficient, and in particular, when moisture penetrated through the outer jacket 8 is infiltrated or external physical shock or temperature change is applied to the cable, the adhesive force is remarkably lowered.

Further, when the metal foil is a lead foil, the weight of the lead foil may be too heavy to reduce the weight of the cable. If the metal foil is a lightweight aluminum foil, the aluminum foil is vulnerable to corrosion have.

The watertight layer 7 applied to the power cable in the related art is insufficiently adhered to the outer jacket 8 so that the watertight layer 7 and the outer jacket 8 are separated from each other There is a problem of peeling.

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.

Therefore, it has a water-tight layer which is effectively suppressed in peeling of the overlapping portions at both ends even when moisture permeates and changes in external physical impact and temperature, and has a water-tight layer excellent in corrosion resistance. Therefore, a structurally stable power cable is desperately needed It is a fact that is demanded.

It is an object of the present invention to provide a power cable having a watertight layer in which water is penetrated, and peeling of overlapping portions at both ends is effectively suppressed even when external physical impact or temperature change occurs.

It is another object of the present invention to provide a power cable having a waterproof layer having a light weight and excellent corrosion resistance.

Further, it is an object of the present invention to provide a structurally stable power cable having excellent interlayer adhesion.

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; Wherein the watertight layer is formed by a metal laminate comprising a metal foil and an adhesion-promoting layer laminated on the metal foil, wherein both ends of the metal laminate overlap and the metal The lower surface of the one end of the laminate and the upper surface of the other end are bonded to the hot-melt adhesive layer formed by hot-melt adhesive,

And a residual force of peel force defined by the following formula (1) is 50% or more.

[Equation 1]

Peel force residual rate = final peel force / initial peel force × 100

In the above equation (1)

The initial peeling force is the peeling force of the hot-melt adhesive layer with respect to the metal laminate measured at room temperature,

The final peel force is the peeling force of the hot-melt adhesive layer on the metal laminate after immersing in a basic aqueous solution of pH 8.5 at 80 DEG C for 300 hours.

Wherein the hot melt adhesive comprises a hot melt adhesive or a pressure sensitive adhesive having a creep resistance temperature and a softening temperature of at least 80 ° C.

Also, the present invention provides a power cable characterized in that the hot melt adhesive comprises polyamide, polyethylene vinyl acetate, rubber-based resin, or a combination thereof.

And wherein the metal foil is a copper foil, the thickness of the copper foil is 0.05 to 0.38 mm, and the thickness of the adhesion-assisting layer is 0.05 to 0.1 mm.

On the other hand, the adhesive-supporting layer may be formed by bonding an adhesive having an adhesive strength of not less than 70% to the peel force of the outer jacket to the metal foil measured after immersing the power cable in a basic aqueous solution having a pH of 8.5 at 80 ° C for 7 days And a power cable.

Wherein the adhesive forming the adhesion-assisting layer comprises a copolymer of an olefin and a polar monomer or a blend resin.

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

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

Further, the present invention provides a power cable, 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).

On the other hand, the outer jacket comprises a high density polyethylene (HDPE) resin and has a thickness of 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 inner semiconductive layer, the insulating layer and the outer semiconductive layer are made of a base resin of a similar type.

The power cable further includes a buffer layer surrounding the watertight layer and an adhesive layer surrounding the buffer layer.

The buffer layer has a melting point of 80 ° C or more, a density of 0.85 to 0.94, and a shore A of 65 or more.

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).

Further, the thickness of the buffer layer is 1 to 3 mm.

On the other hand, the adhesive layer includes a resin having a density of 0.90 or more and a degree of crystallinity of more than 50%, and does not include an additive that forms a moisture transfer path.

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

Also provided is a power cable characterized in that the adhesive layer comprises a high density polyethylene (HDPE) resin.

Further, the thickness of the adhesive layer is 1 to 6 mm.

The power cable according to the present invention is characterized in that a hot melt adhesive having a specific physical property is applied to an overlapping portion of both end portions of a metal laminate constituting a watertight layer so that adhesion between metal laminates Can be maintained.

Further, the power cable according to the present invention exhibits an effect of light weight and excellent corrosion resistance by a lightweight metal foil constituting a watertight layer and a resin coated on the surface of the metal foil.

Furthermore, the power cable according to the present invention exhibits excellent structural stability by being excellent in interlayer adhesive force even when external physical impact or temperature change is caused by a buffer layer and an adhesive layer made of a specific material applied between the watertight layer and the outer jacket.

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

2 and 3 schematically show a cross-sectional structure of an embodiment of a power cable according to the present invention. 2 and 3, 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, and an outermost outer jacket 100. The metal shield layer may include a metal shield layer,

The power cable according to the present invention further includes an adhesive layer 90 for improving the adhesion between the watertight layer 70 and the outer jacket 100 and a waterproof layer 70 for protecting the watertight layer 70 from an external impact on the cable. And a buffer layer 80 for maintaining an adhesive force between the water-tight layer 70 and the adhesive layer 90 even when the external impact is applied.

4 schematically shows a cross-sectional structure of a watertight layer 70 in a power cable according to the present invention. The water-tight layer (70) functions to prevent moisture penetrated through the outer jacket (100) from penetrating into the insulating layer (30). 4, the watertight layer 70 is formed by a metal laminate comprising a metal foil 72, for example a copper foil and an adhesion-promoting layer 71 laminated on the metal foil 72 .

In the watertight layer 70, the copper foil as the metal foil 72 is superior in corrosion resistance to the conventional aluminum foil layer, and is advantageous in that it is lighter than the conventional lead foil layer. On the metal foil 72, an adhesion-assisting layer 71 is formed. It is not easy to adhere the metal foil 72 to the buffer layer 80 or the adhesive layer 90 so that an adhesive auxiliary layer 71 made of a resin that can be easily adhered to the metal foil 72 is formed on the metal foil 72 And lamination is carried out.

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

Here, the method of laminating the adhesion-assisting layer 71 is not particularly limited, and for example, deposition, electro deposition, extrusion, or the like can be used. The adhesion-assisting layer 71 is formed on the water-tight layer 70 and the outer jacket 100 or the water-tight layer 70 and the buffer layer 80 (FIG. 1) even under a severe condition in which an impact is applied from the outside of the cable, ) Or a function of maintaining close adhesion of the adhesive layer (90) and a function of suppressing corrosion of the metal foil (72).

The adhesive auxiliary layer 71 is formed on the outer jacket 100 or the metal foil 72 for the metal foil 72 after the power cable is immersed in a basic aqueous solution having a pH of 8.5 at a temperature of 80 ° C for 7 days The adhesive layer 90 may have an adhesive strength of not less than 70%. The peeling force residual rate refers to the initial value of the peeling force of the outer jacket 100 with respect to the metal foil 72 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 71 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 71 may be formed by a general coating process such as spraying, impregnation, or extrusion.

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 71 may be ethylene acrylic acid (EAA), ethylene vinyl acetate (EVA), ethylene butyl acrylate (EBA), or the like.

As shown in FIG. 3, both ends of the metal laminate may be overlapped to realize better watertightness. In the overlap region, the lower surface and the upper surface of the other end of the metal laminate are hot- And can be closely adhered by an adhesive.

The hot-melt adhesive may be 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 hot melt is preferably made of a resin such as polyamide, polyethylene vinyl acetate or rubber series having a creep resistance temperature and a softening temperature of 80 DEG C or higher, preferably for use in a power cable.

The hot melt adhesive layer is applied to the surface of the metal laminate constituting the watertight layer 70 to form a hot melt adhesive layer, the initial peeling force of the hot melt adhesive layer to the metal laminate is measured, When the laminate was immersed in a basic aqueous solution of pH 8.5 at 80 캜 for 300 hours and the final peel strength of the hot-melt adhesive layer for the metal laminate was measured, the residual peel force defined as the final peel strength / initial peel strength x 100 It can be more than 50%.

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.

The buffer layer 80 is disposed between the watertight layer 70 and the adhesive layer 90 to absorb external impacts on the cable to prevent damage to the watertight layer 70, particularly the metal foil 72, And performs a function of suppressing peeling.

Particularly, when the external impact on the cable exceeds the extent that it can be absorbed by the buffer layer 80, a part of the impact is transmitted to the watertight layer 70, particularly the metal foil 72, The buffer layer 80 may be formed in the foil 72. The buffer layer 80 may be formed in the foil 72 to have a recessed portion in the foil 72. The recessed portion may be a passage through which water 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 72 can not be sufficiently filled.

Since the buffer layer 80 is disposed between the water-tight layer 70, particularly the adhesion-assisting layer 71 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 71 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 1 to 6 mm. If the thickness of the adhesive layer 90 is less than 1 mm, the peeling force of the adhesive layer 90 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 formed by forming the metal foil 72 of the watertight layer 70 from a copper foil that is lighter in weight than conventional lead and superior in corrosion resistance compared to conventional aluminum, And excellent in 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 71 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 metal foil 72 from being damaged, and further, when a part of the impact on the cable is transmitted to the metal foil 72 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. Preparation of sample sheet for overlapping part of watertight layer and evaluation of adhesion property

The hot-melt adhesive sheet and the copper foil were preheated at 120 DEG C for 10 minutes, and then the copper foil was bonded to the upper and lower portions of the hot-melt adhesive sheet at 160 DEG C And pressurized to 5 MPa to prepare sample sheets of Examples 1 and 2.

1) Evaluation of adhesion property

The initial peel force of the hot-melt adhesive sheet for the copper foil was measured at room temperature in each of the sample sheets of Examples 1 and 2. The sample sheets of each of Examples 1 and 2 were immersed in a NaOH aqueous solution of pH 8.5 at 80 캜 for 300 hours, and the final peel strength of the hot-melt adhesive sheet to the copper foil was measured. The peel force residual rate was calculated using the initial peel force and the final peel force measurement value. The measurement and calculation results are shown in Table 1 below.

Example 1 Example 2 Hot melt Hot melt adhesive 1 Hot melt adhesive 2 Peel force Initial peel force (N / mm) 2.09 1.31 Final peel force (N / mm) 1.47 0.76 Peel force residual rate (%) 70 58

- Hot-melt adhesive 1: Amide-based adhesive (creep resistance temperature: 115 캜, softening temperature: 130 캜)

Hot melt adhesive 2: polyethylene vinyl acetate (creep resistance temperature: 90 占 폚, softening temperature: 110 占 폚)

As shown in Table 1, the power cable according to the present invention having a watertight layer having a creep resistance temperature and a softening temperature of 80 ° C or more and applied to overlapping portions of both ends of the hot melt adhesive has an excellent adhesive force even at the time of moisture penetration Respectively.

2. Preparation of watertight layer and adhesive layer sample sheet and evaluation of watertightness and adhesion properties

(High density polyethylene having a density of 0.956), a copper foil, an adhesion-promoting layer (ethylene vinyl acetate), an adhesive layer (ethylene-vinyl acetate), and the like were formed through a hot press operation under the conditions of a press temperature of 160 占 폚 (10 minutes), a cooling temperature of 40 占 폚 (High-density polyethylene having a density of 0.956) were laminated in this order. In addition, sample sheets of Examples and Comparative Examples in which litmus paper was inserted between two adhesive layer specimens shown in Table 2 below were prepared.

Suzy Thickness (mm) Example 4 Resin 1 1.0 Example 5 Resin 1 2.0 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 1.0 Comparative Example 6 Resin 2 2.0

- Resin 1: High density polyethylene (density 0.956)

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

1) Evaluation of adhesion property

The peel force of the outer jacket against the copper foil was measured before and after the sample sheet of Example 3 was immersed in a basic aqueous solution of pH 8.5 and 80 ° C. The results of the peeling force measurement are shown in Table 3 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 3, the power cable of Example 3 according to the present invention was excellent in water-permeability and adhesiveness of the adhesive layer, so that the interlayer adhesion between the watertight layer and the outer jacket was maintained at 70% .

2) Evaluation of Watertight Characteristics

After immersing the specimens of Examples 4 and 5 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 4 below.

Time to moisture penetration Example 4 More than 125 days Example 5 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 4, the adhesive layers of Examples 4 and 5 according to the present invention were made of a resin having a density of 0.90 or more and were found to have sufficient water repellency because they had a thickness of a certain value or more.

On the other hand, the adhesive layers of Comparative Examples 1 to 4 had 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 due to the density of the resin constituting them being less than 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 (21)

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; An outer jacket surrounding the watertight layer,
Wherein the watertight layer is formed by a metal laminate comprising a metal foil and an adhesion-promoting layer deposited on the metal foil,
And the lower surface of the one end of the metal laminate and the upper surface of the other end of the metal laminate are bonded to the hot melt adhesive layer formed by the hot melt adhesive,
A power cable having a residual strength of 50% or more as defined by the following formula (1).
[Equation 1]
Peel force residual rate = final peel force / initial peel force × 100
In the above equation (1)
The initial peeling force is the peeling force of the hot-melt adhesive layer with respect to the metal laminate measured at room temperature,
The final peel force is the peeling force of the hot-melt adhesive layer on the metal laminate after immersing in a basic aqueous solution of pH 8.5 at 80 DEG C for 300 hours. The method according to claim 1,
Wherein the hot melt adhesive comprises a hot melt adhesive or a pressure sensitive adhesive having a creep resistance temperature and a softening temperature of at least < RTI ID = 0.0 > 80 C. < / RTI > 3. The method of claim 2,
Wherein the hot melt adhesive comprises a polyamide, a polyethylene vinyl acetate, a rubber-based resin, or a combination thereof. 4. The method according to any one of claims 1 to 3,
Wherein the metal foil is a copper foil, the thickness of the copper foil 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 adhesive-supporting layer comprises an adhesive having an adhesive strength of not less than 70% of the residual capacity of the outer jacket to the metal foil measured after immersing the power cable in a basic aqueous solution of pH 8.5 at 80 ° C for 7 days Features, power cable. 6. The method of claim 5,
Wherein the adhesive forming the adhesion-promoting layer comprises copolymerization of an olefin and a polar monomer or a blend resin. The method according to claim 6,
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. 8. The method of claim 7,
Wherein the content of the polar monomer is 5 to 25% by weight based on the total weight of the random copolymer resin. The method according to claim 6,
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 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 inner semiconductive layer, the insulating layer, and the outer semiconductive layer are made of similar base resin. 4. The method according to any one of claims 1 to 3,
Further comprising a buffer layer surrounding the watertight layer and an adhesive layer surrounding the buffer layer. 15. The method of claim 14,
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. 16. The method of claim 15,
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). 15. The method of claim 14,
Wherein the thickness of the buffer layer is 1 to 3 mm. 15. The method of claim 14,
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. 19. The method of claim 18,
Characterized in that the adhesive layer comprises a resin having a degree of crystallinity of at least 60%. 20. The method of claim 19,
Wherein the adhesive layer comprises a high density polyethylene (HDPE) resin. 15. The method of claim 14,
Wherein the thickness of the adhesive layer is 1 to 6 mm.

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