KR20190037996A - Waterproofing sheath composition having an excellent tear resistance, wear resistance and flame retardant and waterproofing cable comprising a sheath layer formed from the same - Google Patents

Abstract

The present invention relates to a water-shielding sheath composition having excellent tear resistance and wear resistance and a water-shielding cable comprising a sheath layer formed therefrom. Specifically, even when exposed to a submerged environment, problems such as leakage current and insulation breakdown caused by water tree in an insulating layer can be avoided or minimized, thereby extending the service life of the cable. The insulating layer can be protected from an external impact or pressure by having excellent tear resistance and wear resistance. Also, the emission of toxic gas is minimized when a fire occurs, and the cable has excellent flame retardancy.

Description

[0001] The present invention relates to a water-insulated cable comprising a car-receiving sheath composition excellent in heat resistance, abrasion resistance and flame retardancy, and a sheath layer formed therefrom, the sheath composition having an excellent tear resistance, wear resistance and flame retardant,

TECHNICAL FIELD [0001] The present invention relates to a car-receiving sheath composition excellent in resistance to wear, abrasion resistance and flame retardancy, and a sheath cable comprising the sheath layer formed therefrom. Specifically, even when exposed to a submerged environment, it is possible to avoid or minimize problems such as leakage current and dielectric breakdown caused by the water tree in the insulating layer, thereby prolonging the life of the cable and providing excellent heat resistance and abrasion resistance, Which is capable of protecting the insulating layer from fire, minimizing the emission of toxic gases when a fire occurs, and having excellent flame retardancy, and a sheath layer formed therefrom.

The low voltage cable used for the power supply of the railroad may include a conductor, an insulation layer surrounding the conductor, a sheath layer surrounding the insulation layer, and the like. The medium voltage cable may include an insulation layer and a sheath layer And may further include a metal shielding layer which is disposed in the conductor and shields electromagnetic waves formed by a current flowing in the conductor.

In a cable used in an environment that can be exposed to moisture, such as a submerged environment, moisture permeates into the insulating layer, so that insulation performance is deteriorated, water penetrating into the water tree, that is, the insulating layer is ionized, an alternating electric field is applied to the ions, As a result, a gap is created in the insulating layer, and moisture penetrates through the gap, thereby allowing moisture to penetrate into the conductor, thereby causing leakage current, insulation breakdown, and the like.

Further, since the sheath layer of the cable absorbs moisture, it causes damage due to corrosion of the metal shielding layer due to moisture infiltration, human contact electric shock accident or breakage accident upon rise of the induced voltage at the open end of the grounded metal shield layer at one side .

BACKGROUND ART [0002] Conventionally, as a base resin, a polyvinyl chloride (PVC) resin or a low thermal halogen free resin is used for a low-voltage or medium-voltage cable for a railroad power supply. The polyvinyl chloride (PVC) But the microporosity inside the sheath layer formed therefrom is insufficient in water repellency and causes toxic gas during combustion for disposal of the cable, resulting in environmental problems, poor thermal resistance and abrasion resistance There is a problem that it is easily damaged from external impact or pressure, and the low heat halogen free resin has a problem of poor resistance to heat.

Therefore, even when exposed to a submerged environment, problems such as leakage current and dielectric breakdown caused by the water tree in the insulating layer can be avoided or minimized, thereby extending the service life of the cable and providing excellent heat resistance and abrasion resistance. There is a desperate need for an augmented cable comprising a car-receiving sheath composition capable of protecting the insulation layer and a sheath layer formed therefrom.

The present invention includes a car-receiving sheath composition and a sheath layer formed therefrom that can alleviate or minimize problems such as leakage current and dielectric breakdown caused by the water tree in the insulation layer, And to provide an order cable to be used.

Further, the present invention provides a car-containing sheath composition which is excellent in heat resistance and abrasion resistance and can protect the insulation layer against external impacts or pressures, minimizes the emission of toxic gases when a fire occurs and has excellent flame retardancy, and a sheath layer formed therefrom The present invention provides an order cable including the cable.

In order to solve the above problems,

Wherein the base resin comprises a polyethylene resin and an ethylene-alpha olefin copolymer, wherein the base resin comprises 70 to 150 parts by weight of a flame retardant based on 100 parts by weight of the base resin, wherein the polyethylene resin and the ethylene- And the melting point (Tm) of each is 90 DEG C or higher.

Here, the cis body specimen formed from the car-receiving sheath composition has a tear strength at room temperature of 12 N / mm or more, a Shore D hardness at room temperature of 50 or more, a moisture absorption amount of 1 mg / , And an oxygen index of 30 or more.

The polyethylene resin may be at least one selected from the group consisting of linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE) and modified polyethylene (MA-PE) Containing sheath composition.

The ethylene-alpha olefin copolymer may be a copolymer of ethylene and an? -Olefin other than ethylene, such as 1-propylene, 1-butene, 1-pentene, , 1-decene, 1-dodecene, and combinations thereof.

Further, the present invention provides a car-receiving sheath composition, wherein the blending ratio of the polyethylene resin to the ethylene-alpha olefin copolymer is 70:30 to 60:40.

On the other hand, the flame retardant includes at least one metal hydroxide selected from the group consisting of aluminum hydroxide, magnesium hydroxide, a mixture of hunting and hydro-magneite, hydro-magneite, magnesium hydroxide carbonate and hydrotalcite. Lt; / RTI >

Here, the metal hydroxide has a surface treated to be hydrophobic.

The present invention also provides a car-receiving sheath composition, which further comprises at least one additive selected from the group consisting of an antioxidant, a stabilizer, a termite inhibitor and a lubricant.

Further, the content of the antioxidant is 2 to 5 parts by weight, the content of the stabilizer is 1 to 15 parts by weight, the content of the antitheft agent is 2 to 5 parts by weight based on the total weight of the sheath composition, Is 1 to 3 parts by weight.

On the other hand, An insulating layer surrounding the conductor; A metal shielding layer surrounding the insulating layer; And a sheath layer comprising the metal shielding layer, wherein the sheath layer is formed from the sheathing sheath composition of any one of claims 1 or 2.

The car-receiving sheath composition according to the present invention avoids problems such as leakage current and insulation breakdown due to the water tree in the insulating layer even when the cable including the sheath layer formed therefrom through the specific combination and blending of the base resin is exposed to the submergence environment So that the cable life can be prolonged.

In addition, the car-receiving sheath composition according to the present invention is excellent in heat resistance and wear resistance through a specific combination and blending of the base-base resin, thereby protecting the insulating layer from external impact or pressure, minimizing the emission of toxic gas And exhibits excellent effects with excellent flame retardancy.

1 schematically shows a cross-sectional structure according to one embodiment of an aberration cable according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. 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.

The present invention relates to a car-receiving sheath composition excellent in heat resistance, abrasion resistance and flame retardancy, and may comprise a polyethylene resin and an ethylene-alpha olefin copolymer as a base resin.

Here, the polyethylene resin may be a group consisting of linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), and modified polyethylene, for example, maleic anhydride grafted polyethylene (MA-PE) (MA-PE), preferably linear low density polyethylene (LLDPE) and maleic anhydride grafted polyethylene (MA-PE).

Also, the ethylene-alpha olefin copolymer may be a copolymer of ethylene and an? -Olefin other than ethylene, such as 1-propylene, 1-butene, 1-pentene, , 1-decene, 1-dodecene, and combinations thereof, and the like. Also, the ethylene-alpha olefin copolymer may be a random copolymer or a block copolymer in which ethylene and an alpha -olefin are polymerized without regularity, and may preferably be a polyolefin elastomer (POE).

The polyethylene resin and the ethylene-alpha olefin copolymer contained as the base resin may each have a melting point (Tm) of 90 DEG C or higher. If the melting point (Tm) of the base resin is less than 90 占 폚, the heat resistance, abrasion resistance, water resistance, etc. of the sheath composition may be greatly reduced.

The blending ratio of the polyethylene resin and the ethylene-alpha olefin copolymer as the base resin may be 70:30 to 60:40. If the ethylene-alpha olefin copolymer is less than 30 phr, the heat resistance and abrasion resistance of the sheath composition may be greatly deteriorated. On the other hand, when the ethylene-alpha olefin copolymer is more than 70 phr, flame retardancy, Etc. can be greatly reduced.

The sheath composition may further include a flame retardant agent for improving flame retardancy.

The flame retardant includes an inorganic flame retardant such as aluminum hydroxide, magnesium hydroxide, a mixture of hunting and hydro magneite, a metal hydroxide such as hydro-magneite, magnesium hydroxide carbonate, hydrotalcite, etc., an organic phosphorus-based agent such as an organic phosphorus- can do.

The organic flame retardant is excellent in compatibility with the base resin, whereas the metal hydroxide has a property of having a hydroxyl group (-OH) on its surface and easily absorbs moisture. Therefore, the organic hydroxide has low compatibility with the hydrophobic base resin, There is a problem that the water resistance of the layer is lowered.

Therefore, the metal hydroxide flame retardant can be surface-treated with a hydrophobic property such as silane to improve the compatibility with the base resin and improve the water resistance of the sheath layer.

The content of the flame retardant may be 70 to 150 parts by weight based on 100 parts by weight of the base resin. When the content of the flame retardant is less than 70 parts by weight, the flame retardancy of the sheath layer may be insufficient, If it is more than 1 part by weight, the load during the extrusion of the sheath composition and the defective appearance of the sheath layer formed therefrom may occur.

In addition, the sheath composition may further contain an antioxidant, a stabilizer, a termite inhibitor, a lubricant, etc. in addition to the flame retardant.

The antioxidant may include at least one selected from the group consisting of a phenolic antioxidant, a phosphorus antioxidant, a thio antioxidant, and the like. If the amount of the antioxidant is less than 2 parts by weight, the life of the cable may be deteriorated due to oxidation of the sheath layer. On the other hand, if the content of the antioxidant is more than 5 parts by weight, Tensile strength, tear strength, elongation, abrasion resistance, flame retardancy, and the like may be lowered.

The stabilizer may include at least one selected from the group consisting of a lead stabilizer, a non-lead stabilizer, an epoxy stearate, a metal soap stabilizer, and the like. When the content of the stabilizer is less than 1 part by weight, the heat resistance of the sheath layer may be drastically decreased. On the other hand, when the content of the stabilizer is more than 15 parts by weight, .

The above-mentioned sheath composition can prevent the mechanical damage of the cable system which may be caused by termite attack after the cable is installed by including the termite inhibitor. The termite inhibitor is used for the purpose of preventing the environment influence by the soil- (2-methyl-3-phenylphenyl) methyl (1S, 3S) -3 - [(Z) -2-chloro-3,3,3-trifluoropyrazole 2-methyl-3-phenylphenyl) methyl (1S, 3S) -3 - [(Z) -2- 3,3-trifluoroprop-1-enyl] -2,2-dimethylcyclopropane-1-carboxylate}.

The content of the anti-termitic agent may be 2 to 5 parts by weight based on the total weight of the sheath composition. When the content of the anti-periodic agent is less than 2 parts by weight, the termiticidal property may be insignificant, Is more than 5 parts by weight, physical properties such as tensile strength, tear strength, heat resistance, and weather resistance of the sheath layer may be lowered.

In the sheath composition according to the present invention, the cis layer specimen formed therefrom has a tear strength of 12 N / mm or more at room temperature and a Shore D hardness The water absorption amount after flooding at 50 or more at normal temperature and 24 hours at 70 ° C may be 1 mg / mm 2 or less and the oxygen index 30 or more.

1 schematically shows a cross-sectional structure according to one embodiment of an aberration cable according to the present invention.

1, an order cable according to the present invention includes a conductor 100, an insulating layer 200 surrounding the conductor 100, a metal shielding layer 300 surrounding the insulating layer 200, A sheath layer 400 surrounding the shield layer 300, and the sheath layer 400 may be formed by extrusion of the sheath composition described above.

The conductor 100 may be made of a conductive material such as copper or aluminum through which a current can flow and may be a stranded wire having a single wire or a plurality of wires connected thereto, For example, a polymer resin.

The diameter of the conductor 100 is determined according to the rated voltage of the cable. For example, the conductor 100 used in the cable for rail power supply having a rated voltage of 1800/3000 V has a diameter The diameter of the strand can be about 0.53 to 1.35 mm, and the nominal cross-sectional area of the single or stranded wire can be 1.5 to 300 mm < 2 >, especially 1.5 to 4 mm &

[Example]

1. Manufacturing Example

A cable specimen including the cis specimen and the sheath layer of the components and the mixing ratio according to the following Table 1 was prepared. The unit of mixing ratio shown in Table 1 below is parts by weight.

Example Comparative Example 1 Comparative Example 2 Resin 1 40 30 30 Resin 2 30 30 30 Resin 3 30 Resin 4 40 Resin 5 40 Antioxidant 4 3 3 Lubricant 4.5 5 5.8 Flame retardant 80 80 80 Flame retardant aid 4 2 3.3 UV stabilizer 3.5 Filler 5 5 5 White antiseptic 2 One

- Resin 1: Linear low density polyethylene (LLDPE)

- Resin 2: Maleic anhydride grafted polyethylene (MA-PE)

- Resin 3: polyolefin elastomer

- Resin 4: Ethylene Ethyl Acrylate (EEA)

- Resin 5: ethylene vinyl acetate (EVA)

2. Property evaluation

(1) Evaluation of water resistance (moisture absorption amount)

According to the standard HD 22.16, the cisse pieces according to each of the examples and the comparative examples were immersed in a water bath at 50 캜 for 12 weeks, and then the mass change rate and the tensile strength / elongation percentage change rate were measured for each parking lot. The average mass change rate over 12 weeks is less than 1% of the untreated cis sample and after 12 weeks the rate of change in tensile strength / elongation should be greater than 90% of the untreated cis sheath.

(2) Abrasion resistance (hardness) evaluation

A load of 20 kg was applied to a needle disposed on a sheath layer of a cable specimen (wire strand of small bow 7 having a diameter of 0.53 to 1.35 mm) according to the standard HD 620 S2 according to each of Examples and Comparative Examples When the distance of 50 ± 10 cm is repeated 8 times at a speed of 0.3 m / s, the inside of the sheath should not be exposed.

(3) Evaluation of tear resistance (tear strength)

Tensile strength was measured at a speed of 500 mm / min using a tensile tester for six cis sample pieces (thickness 1 to 4 mm) according to each of the examples and comparative examples according to the standard HD 620 S2. The average value of the tear strength measured for the test specimen shall be 18 N / mm or more.

(4) Evaluation of flammability (oxygen index)

The oxygen index was measured for a specimen (150 mm x 6.5 mm x 4 mm) according to ASTM D2853. The oxygen index should be 30 or higher.

The results of the physical property evaluation are shown in Table 2 below.

Properties unit spec. Example Comparative Example 1 Comparative Example 2 Room temperature
(250 mm / min) The tensile strength kgf / mm2 1.1? 1.48 1.13 1.38 Elongation rate % 300? 424 212.96 378.33 After heating
(100 DEG C / 240 hours) The tensile strength kgf / mm2 70-130 1.41 111.48 95.68 Elongation rate % 300? 434.67 68.37 334.21 Hardness (Shore D) 55? 63.10 58.30 - Tear strength (ASTM D470) N / mm 12? 18.08 11.03 16.12 Oxygen index 30? 31.00 - 29.00

As shown in Table 2, the sheath compositions of Examples 1 and 2 were found to have excellent tensile strength, tear strength, elongation, heat resistance, abrasion resistance and oil resistance, -Alphaolefin copolymer, it was confirmed that the tear strength, elongation, heat resistance and the like were significantly lowered and the flame retardancy was greatly lowered.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. You can do it. 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.

100: conductor 200: insulating layer
300: sheath layer 400: metal shielding layer

Claims (10)

As the tea-receiving sheath composition,
Wherein the base resin comprises a polyethylene resin and an ethylene-alpha olefin copolymer,
And 70 to 150 parts by weight of a flame retardant based on 100 parts by weight of the base resin,
Wherein the melting point (Tm) of each of the polyethylene resin and the ethylene-alpha olefin copolymer is 90 DEG C or higher. The method according to claim 1,
The cis body specimen formed from the above-mentioned heat shielding sheath composition has a tear strength at room temperature of 12 N / mm or more, a Shore D hardness at room temperature of 50 or more, a moisture absorption amount of 1 mg / Lt; RTI ID = 0.0 > 30. ≪ / RTI > 3. The method according to claim 1 or 2,
Wherein the polyethylene resin comprises at least one member selected from the group consisting of linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE) and modified polyethylene. 3. The method according to claim 1 or 2,
The ethylene-alpha olefin copolymer is a copolymer of ethylene and? -Olefins other than ethylene, such as 1-propylene, 1-butene, 1-pentene, - decene, 1-dodecene, and combinations thereof. 3. The method according to claim 1 or 2,
Wherein the blending ratio of the polyethylene resin to the ethylene-alpha olefin copolymer is 70:30 to 60:40. 3. The method according to claim 1 or 2,
Wherein said flame retardant comprises at least one metal hydroxide selected from the group consisting of aluminum hydroxide, magnesium hydroxide, a mixture of hunting and hydro-magneite, hydro-magneite, magnesium hydroxide carbonate and hydrotalcite. The method according to claim 6,
Wherein the metal hydroxide has a surface treated to be hydrophobic. 3. The method according to claim 1 or 2,
Wherein the composition further comprises at least one additive selected from the group consisting of an antioxidant, a stabilizer, a termite inhibitor and a lubricant. 9. The method of claim 8,
Based on the total weight of the sheath composition, the content of the antioxidant is 2 to 5 parts by weight, the content of the stabilizer is 1 to 15 parts by weight, the content of the antitheft agent is 2 to 5 parts by weight, And 1 to 3 parts by weight. Conductor;
An insulating layer surrounding the conductor;
A metal shielding layer surrounding the insulating layer; And
And a sheath layer including the metal shield layer,
Characterized in that the sheath layer is formed from the sheathing sheath composition of claim 1 or 2.

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