KR102817107B1 - Insulating composition and power cable formed from the same - Google Patents

Abstract

The present invention relates to an insulating composition comprising polypropylene having excellent flame retardancy and a melting point of 145°C or more and 165°C or less; and polyolefin having a melting point of 70°C or more and 105°C or less as a base resin, and to a power cable comprising an insulating layer formed using the same.
The cable according to the present invention satisfies the heat resistance characteristics required as an indoor wiring cable, the flame retardancy required by IEC 60332-3-24, and the withstand voltage characteristics required by IEC 62930.

Description

{INSULATING COMPOSITION AND POWER CABLE FORMED FROM THE SAME}

The present invention relates to an insulating composition having excellent flame retardancy and a power cable formed using the same.

Normally, polyethylene has a melting point of 100℃ to 125℃, so it cannot satisfy the continuous use temperature of 90℃ of cables specified in most international standards such as IEC and ICEA. In the past, cross-linked polyethylene, which is polyethylene cross-linked in various ways, has been used as a component of the insulation layer to overcome this problem.

However, when cross-linked polyethylene is used in this way, new problems arise, such as increased costs due to the additional cross-linking process and related equipment investment, and a decrease in the insulation performance of the cable due to foreign substances such as by-products generated during cross-linking.

In particular, indoor wiring cables, which are wires that are branched from an outdoor distribution board and connected to each floor through trays installed on indoor walls, ceilings, etc., require flame retardant performance of the cable because flame propagation delay is essential to protect human life in the event of a fire inside the building. Indoor wiring cables using existing XLPE insulation are cross-linked, which suppresses the melting of the insulation under high-temperature conditions caused by flames. However, in the case of cables that include an insulation layer using a non-cross-linked insulating composition, the melting of the insulation may occur under high-temperature conditions caused by flames, which may cause problems with the flame retardant performance of the cable.

Therefore, to prevent this, there has been a need to develop an insulating composition that does not melt at high temperatures and a cable using the composition.

Patent Document 1: Korean Patent Publication No. 10-2012-0102371

The technical problem to be solved by the present invention is to provide an insulating composition having excellent flame retardancy that does not melt at high temperatures and an indoor wiring power cable formed using the same.

As a means for solving the above-mentioned technical problem, one embodiment of the present invention provides an insulating composition for forming an insulating layer of a power cable, the insulating composition comprising polypropylene having a melting point of 145°C or more and 165°C or less; and polyolefin having a melting point of 70°C or more and 105°C or less as base resins.

In addition, one embodiment of the present invention provides a power cable including a conductor; and an insulating layer formed to surround an outer periphery of the conductor, wherein the insulating layer is formed using the insulating composition.

The insulating composition according to the present invention has excellent flame retardancy that does not melt at high temperatures.

The cable according to the present invention satisfies the heat resistance characteristics required as a cable for indoor wiring.

In addition, the cable according to the present invention satisfies the flame retardancy required by IEC 60332-3-24.

Finally, the cable according to the present invention satisfies the withstand voltage characteristics required by IEC 62930.

The attached drawings are intended to explain the contents of the present invention in more detail to a person skilled in the art, but the technical idea of the present invention is not limited thereto.
FIG. 1 is a cross-sectional view of a cable according to some embodiments of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description is intended only to specify the embodiments, and is not intended to limit or restrict the scope of rights according to the present invention. It should be interpreted that what a person having ordinary knowledge in the technical field related to the present invention can easily infer from the detailed description and embodiments of the invention falls within the scope of rights according to the present invention.

The terms used in the present invention are described as general terms widely used in the technical field related to the present invention, but the meaning of the terms used in the present invention may vary depending on the intention of the engineer engaged in the relevant field, the emergence of new technologies, examination criteria, or precedents. Some terms may be arbitrarily selected by the applicant, and in this case, the meaning of the arbitrarily selected terms will be explained in detail. The terms used in the present invention should be interpreted not only with their dictionary meanings but also with a meaning reflecting the overall context of the specification.

The terms "comprises" or "comprising" used in the present invention should not be construed to necessarily include all of the components or steps described in the specification, and it should also be construed that some of the components or steps are not included, and additional components or steps are further included.

Hereinafter, the present invention will be described in detail.

One embodiment of the present invention provides an insulating composition comprising, as base resins, polypropylene having a melting point of 145°C or more and 165°C or less; and polyolefin having a melting point of 70°C or more and 105°C or less.

Specifically, an insulating composition according to one embodiment of the present invention uses a mixture of polypropylene having a melting point of 145°C or higher and 165°C or lower and polyolefin having a low melting point and small crystallinity due to a melting point of 70°C or higher and 105°C or lower to secure heat resistance at high temperatures, thereby providing an insulating composition capable of satisfying heat resistance characteristics at 150°C required for cable materials having a continuous use temperature of 110°C.

In one embodiment of the present invention, when the melting point of the polypropylene is less than 145°C, heat resistance may be reduced, insulation breakdown voltage may be reduced, and withstand voltage characteristics may be reduced.

In addition, when the melting point of the polyolefin is less than 70°C, the workability of extrusion or compounding may deteriorate, and when it exceeds 105°C, the mechanical properties such as strength and elongation may deteriorate due to the reduced loading of the filler.

When the base resin of the present invention includes a polyolefin having a melting point of 70°C or higher and 105°C or lower, the loading property of the filler is improved and the flexibility of the insulating composition is improved.

In one embodiment of the present invention, the content of polypropylene having a melting point of 145°C or more and 165°C or less is 30 parts by weight or more and 60 parts by weight or less based on 100 parts by weight of the base resin, and the content of polyolefin having a melting point of 70°C or more and 105°C or less is 40 parts by weight or more and 70 parts by weight or less based on 100 parts by weight of the base resin.

In one embodiment of the present invention, specifically, the polypropylene having a melting point of 145°C or more and 165°C or less may be preferably used in an amount of 40 parts by weight or more and 55 parts by weight or less based on 100 parts by weight of the base resin in terms of heat resistance, insulation breakdown voltage, and withstand voltage characteristics.

If the content of polypropylene having a melting point of 145°C or higher and 165°C or lower is less than 30 parts by weight based on 100 parts by weight of the base resin, heat resistance may be reduced, insulation breakdown voltage may be reduced, withstand voltage characteristics may be reduced, and defects may occur in compounding work.

In addition, when the content of the polyolefin having a melting point of 70°C or more and 105°C or less is less than 40 parts by weight based on 100 parts by weight of the base resin, the loading property of the filler may be reduced and the flexibility may be reduced, and when the content of the polyolefin having a melting point of 70°C or more and 105°C or less exceeds 70 parts by weight, the heat resistance may be reduced, the insulation breakdown voltage may be reduced, and the withstand voltage characteristics may be reduced.

In one embodiment of the present invention, the polyolefin having a melting point of 70°C or more and 105°C or less is a polyolefin elastomer (POE).

In one embodiment of the present invention, the specific gravity of the polyolefin having a melting point of 70°C or more and 105°C or less may be 0.880 or more and 0.902 or less. When the specific gravity is less than 0.880, the workability of extrusion or compounding may deteriorate, and when the specific gravity is more than 0.902, the mechanical properties such as strength and elongation may deteriorate due to the deterioration of the loading property of the filler.

In one embodiment of the present invention, the insulating composition may further include one or more selected from the group consisting of an antioxidant, a flame retardant, a filler, and a processing aid.

The above antioxidants, flame retardants, fillers and processing aids can be those available in the art.

For example, antioxidants include phenol-based antioxidants such as n-octadecyl-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate, Tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane, and Tris(3,4-di-tert-butyl-4-hydroxybenzyl)isocyanurate. Phosphorus antioxidants such as tris(2,4-di-tert.-butylphenyl)phosphite, sulfur antioxidants such as distearyl thiodipropionate, and 2,2-Bis[[3-(dodecylthio)-1-oxopropoxy]methyl]propane-1,3-diyl bis[3-(dodecylthio)propionate] can be used, but are not limited thereto.

In addition, the flame retardant may include, but is not limited to, magnesium hydroxide, aluminum hydroxide, phosphorus-based flame retardants, melamine flame retardants (melamine cyanurate, melamine phosphate), silane-surface-treated magnesium hydroxide, or Brucite.

Additionally, the filler may be, but is not limited to, calcium carbonate surface-treated with clay, talc or an activator.

In one embodiment of the present specification, the insulating composition may further include a filler. When the filler is further included, the viscosity required for the insulating layer, that is, the viscosity can be provided to a degree that there is no dripping when the flame retardancy test of IEC 60332-1 is performed on an insulated semi-finished product cable including an insulating layer composed of the insulating composition.

In one embodiment of the present invention, polypropylene having a melting point of 145°C or more and 165°C or less and polyolefin having a melting point of 70°C or more and 105°C or less may be included as base resins, and the polypropylene and polyolefin may be crosslinked or non-crosslinked.

In one embodiment of the present invention, the polypropylene and polyolefin may be a mixed non-crosslinked insulating composition. In this case, since regeneration is possible, the composition is environmentally friendly, and costs can be reduced due to process simplification, and problems of deterioration of insulating performance due to crosslinking byproducts do not occur.

In addition, one embodiment of the present invention provides a power cable including a conductor; and an insulating layer formed to surround an outer periphery of the conductor, wherein the insulating layer is formed using the insulating composition.

In the present invention, the conductor may be made of a conductive material through which current can flow, for example, a metal such as copper or aluminum, and may be a single wire or a stranded wire in which multiple wires are connected. In addition, the cable may include one conductor or may include one or more conductors.

The above insulating layer is for electrical insulation of the cable and is formed using the above-described insulating composition.

In the past, cables with a continuous use temperature of 90°C were used by crosslinking the insulation using methods such as water crosslinking or radiation crosslinking. An insulating composition according to one embodiment of the present invention can satisfy the heat resistance characteristics at 150°C required for cable materials with a continuous use temperature of 110°C.

In one embodiment of the present invention, the power cable further includes a sheath layer provided to surround the outer periphery of the insulating layer.

Figure 1 is a cross-sectional view of a cable according to some embodiments of the present invention. Specifically, a cable according to one embodiment of the present invention may include a conductor (100), an insulation layer (200) provided to surround the outer periphery of the conductor, and a sheath layer (300) provided to surround the outer periphery of the insulation layer.

In one embodiment of the present invention, the cis layer according to one embodiment of the present invention is a layer for protecting the insulating layer, and the cis layer is formed using a base resin including polyolefin; and a cis composition including a flame retardant.

In one embodiment of the present invention, the content of the flame retardant is 80 parts by weight or more and 130 parts by weight or less, based on 100 parts by weight of the base resin of the cis composition. If the content of the flame retardant is less than 80 parts by weight, based on 100 parts by weight of the base resin of the cis composition, the flame retardancy may be poor, and if it exceeds 130 parts by weight, the elongation may be reduced.

In one embodiment of the present invention, the base resin containing the polyolefin may be polyethylene and polyolefin elastomer (POE).

In one embodiment, the flame retardant includes, but is not limited to, magnesium hydroxide, aluminum hydroxide, phosphorus-based flame retardants, melamine flame retardants, and the like.

In one embodiment of the present invention, the cable satisfies the flame retardancy required by IEC 60332-3-24.

In one embodiment of the present invention, the cable satisfies the withstand voltage characteristics required by IEC 62930.

Hereinafter, the present invention will be described in detail by way of examples in order to specifically explain the present invention. However, the examples according to the present invention may be modified in various different forms, and the scope of the present invention is not construed as being limited to the examples described below. The examples in this specification are provided to more completely explain the present invention to a person having average knowledge in the art.

[Examples and Comparative Examples]

An insulating layer was formed as described in Table 1 below.

A sheath layer was formed using a sheath composition containing 90 parts by weight of aluminum hydroxide based on 100 parts by weight of the base resin, using polyethylene and polyolefin elastomer resins as the base resin.

The above insulation layer and sheath layer were sequentially formed on the outer periphery of the conductor to manufacture the final cable.

division Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative Example 1 Comparative Example 2 PP 1 50 - 50 - 30 - 70 PP 2 - 30 - 30 30 10 - 30 PP 3 - 30 - 30 - 30 - 50 30 POE 1 50 - 50 - 40 60 - 50 POE 2 - 40 - 40 - - 30 POE 3 40 Flame retardant 1 20 30 - - - - - 20 30 Flame retardant 2 - - - 50 - 50 - Filler 60 50 30 50 100 50 80 60 50 Antioxidant + processing agent 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 PP 1: Block polypropylene 1 with a melting point of 165℃ (Daehan Yuhwa)
PP 2: Block polypropylene 2 with a melting point of 165℃ (Hyosung Chemical)
PP 3: rTPO (Reactor made ThermoPlastic Olefin) with a melting point of 142℃
POE 1: Polyolefin elastomer (POE) with a melting point of 74℃ and a specific gravity of 0.885
POE 2: POE with a melting point of 100℃ and a specific gravity of 0.902
POE 3: POE with a melting point of 61℃ and a specific gravity of 0.868
Flame retardant 1: Magnesium hydroxide
Flame retardant 2: Brucite
Filler: Calcium carbonate with activated surface

[Property Evaluation]

1. Evaluation of voltage characteristics

The semi-finished product (cable with the sheath layer stripped) manufactured previously with only the insulation layer formed was immersed in a 1% sodium chloride (NaCl) aqueous solution at 85°C and a DC voltage of 1.8 kV was applied for 240 hours to check for voltage breakdown according to the test method of IEC 62930.

2. Flame retardancy evaluation

According to the experimental method of IEC 60332-3-24 (Cat. C), a sample manufactured with the above composition ratio was extruded as an insulation layer, and then a low-toxicity flame-retardant polyolefin composition was extruded as a sheath over the insulation layer to conduct a flame retardancy test on the finished product (a cable in which both the insulation layer and sheath layer were formed). The low-toxicity flame-retardant polyolefin composition applied to the sheath layer used a non-crosslinked polyolefin composition corresponding to an oxygen index of 30.5.

3. Evaluation of mechanical properties at room temperature

Insulating specimens were separately manufactured using the same method as the insulating layer, and the room temperature mechanical properties were evaluated according to the experimental method of IEC 60811-501. The evaluation criteria are a tensile strength of 1.27 kgf/ ^mm2 or more and an elongation of 350% or more.

4. Evaluation of mechanical properties after heating

Insulating specimens were separately manufactured using the method of manufacturing the insulating layer, and mechanical properties were evaluated after heating according to the experimental method of IEC 60811-401, and the heat aging condition was set at 135℃ for 240 hours. The evaluation criteria are tensile strength of 1.27 kgf/ ^mm2 or more and elongation of 350% or more, which are the same as the mechanical properties evaluation at room temperature.

[Results of property evaluation]

The evaluation results according to the above property evaluation criteria are shown in Table 2 below.

division Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative Example 1 Comparative Example 2 Withstand voltage characteristics Pass Pass Pass Fail Fail Fail Pass Pass Pass Flame retardancy Pass Pass Fail Pass Fail Pass Pass Pass Pass Room temperature tensile strength
(kgf/mm ² ) 2.008 1.822 2.137 1.713 2.127 1.521 1.806 1.534 1.679 Room temperature elongation (%) 534.2 561.8 520.7 531.4 661.3 557.2 388.4 627.1 275.2~
613.2 Heating tensile strength
(kgf/mm ² ) 1.93 1.775 2.099 1.629 1.582 1.108 1.644 Melting down 1.721 Heating Elongation (%) 506.5 497.1 504.6 478.6 380.2 457.1 269.0 Melting down 210.7~
535.5

As can be confirmed in the above Table 2, it was confirmed that the cable according to the present invention satisfies the heat resistance characteristics required as an indoor wiring cable, the flame retardancy required by IEC 60332-3-24, and the withstand voltage characteristics required by IEC 62930. In addition, as for the additional matters that could be confirmed, if a flame retardant is not included, there may be a problem in securing the flame retardancy, if flame retardant 1 is changed to flame retardant 2 and included, the flame retardancy is secured, but the withstand voltage characteristics may be a problem, if calcium carbonate is included entirely as a filler without including a flame retardant, neither the flame retardancy nor the withstand voltage characteristics may be satisfied, if the content of polypropylene, which is important for securing heat resistance, is reduced, there may be a problem with the heat resistance, and if a high melting point polyolefin elastomer (POE) is included and a high content of polypropylene is included, the loading characteristics of the filler may be deteriorated, so that the elongation after heat resistance may not meet the standard.

In contrast, in the case of Comparative Example 1, which includes polypropylene having a melting point of less than 145°C, it was confirmed that heat resistance was reduced, resulting in problems of melting in terms of heated tensile strength and heated elongation.

In addition, in the case of Comparative Example 2 containing polyolefin having a melting point of less than 70℃, it was confirmed that there was a strong deviation in the characteristic values due to poor workability such as compounding mixing.

Although the embodiments of the present invention have been described in detail above, the scope of rights according to the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention described in the following claims should also be interpreted as being included in the scope of rights according to the present invention.

100: Conductor
200: Insulation layer
300: Sith layer

Claims (8)

As an insulating composition for forming an insulating layer of a power cable,
Polypropylene having a melting point of 145°C or higher and 165°C or lower; and
An insulating composition comprising a polyolefin having a melting point of 70°C or higher and 105°C or lower as a base resin.
The content of polypropylene having a melting point of 145°C or more and 165°C or less is 30 parts by weight or more and 60 parts by weight or less based on 100 parts by weight of the base resin,
An insulating composition in which the content of the polyolefin having a melting point of 70°C or more and 105°C or less is 40 parts by weight or more and 70 parts by weight or less based on 100 parts by weight of the base resin.
delete In paragraph 1,
An insulating composition wherein the polyolefin having a melting point of 70°C or higher and 105°C or lower is a polyolefin elastomer (POE).
In paragraph 1,
An insulating composition, wherein the insulating composition further comprises one or more selected from the group consisting of an antioxidant, a flame retardant, a filler, and a processing aid.
conductor; and
Including an insulating layer that surrounds the outer periphery of the conductor,
A power cable, wherein the insulating layer is formed using an insulating composition according to any one of claims 1 and 3 to 4.
In paragraph 5,
A power cable further comprising a sheath layer formed to surround the outer periphery of the insulating layer.
In paragraph 6,
The above-mentioned cis layer comprises a base resin including polyolefin; and
A power cable formed using a sheath composition containing a flame retardant.
In paragraph 7,
A power cable wherein the content of the flame retardant is 80 parts by weight or more and 130 parts by weight or less, based on 100 parts by weight of the base resin of the cis composition.