KR101878639B1 - Cable Including Insulation Layer With Insulating Oil - Google Patents

Abstract

The present invention relates to a cable comprising at least one conductor and an insulating layer surrounding the conductor, the insulating layer is a polypropylene and an ethylene-comprising a mixture, and insulating oil, the propylene copolymer, wherein said insulating oil is a ¹ H nuclear magnetic resonance ( ¹ H-NMR) spectroscopic analysis, 80% or more of the total number of ¹ H signals is present in an area of 3.5 ppm or more. In the present invention, since the flexibility of the cable can be improved by using the insulating oil, it is possible to improve the installation of the cable.

Description

(Cable Including Insulation Layer With Insulating Oil)

The present invention relates to a cable comprising an insulating layer containing insulating oil.

1, the conventional cable includes a conductor 11, an inner semiconductive layer 12, an insulating layer 13, an outer semiconductive layer 14, a shielding layer 15, and a sheath layer 16, . ≪ / RTI > In order to satisfy the mechanical characteristics of the high tensile strength required in the cable standard, the prior art used crosslinked polyethylene as a constituent of the insulating layer 13. However, because of the high crystallinity of the crosslinked polyethylene, flexural strength at room temperature is high, so that flexibility of the cable can not be secured when it is applied as an insulator of a cable. This results in difficulty in installation in the field, especially when it is required to bend in order to lay cables in a tight space. As a result, more effort and skill are required to install the cable, and the installation cost is high, so that the productivity is lowered.

Therefore, there is a need for the development of a flexible cable comprising an insulating layer produced without using a crosslinking resin.

An object of the present invention is to provide an excellent flexibility cable including an insulating layer containing an uncrosslinked resin.

According to an aspect of the present invention, there is provided a cable including at least one conductor and an insulating layer surrounding the conductor, wherein the insulating layer includes a mixture of polypropylene and an ethylene-propylene copolymer and an insulating oil, Is characterized in that when ¹ H nuclear magnetic resonance ( ¹ H-NMR) spectroscopic analysis, 80% or more of the total number of ¹ H signals are present in an area of 3.5 ppm or more.

The cable of the present invention does not use the crosslinked polyethylene used as a component of the insulating layer in the past, so that the problem of cost increase due to the crosslinking process and deterioration of insulation performance due to the crosslinked byproduct do not occur, So that the flexibility of the cable is improved and the cable can be easily installed.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. No.
Fig. 1 shows a cross-sectional view of a cable which is commonly used.

Hereinafter, the present invention will be described in detail.

The present invention relates to a cable comprising at least one conductor and an insulating layer surrounding the conductor, wherein the insulating layer comprises a mixture of polypropylene and an ethylene-propylene copolymer and insulating oil. In the present invention, since the flexibility of the cable can be improved by using the insulating oil, it is possible to improve the installation of the cable.

The insulating oil is characterized in that when ¹ H nuclear magnetic resonance ( ¹ H-NMR) spectroscopic analysis, 80% or more of the total number of ¹ H signals are present in an area of 3.5 ppm or more. The use of insulating oil that represents signals in such areas is advantageous in that cables produced have excellent mechanical properties. An example of such an insulating oil is dibenzyltoluene (DBT) having the following formula.

The de total number of ¹ H of benzyl toluene is 20, ¹ H nuclear magnetic resonance ⁽¹ H-NMR) spectroscopy when ¹ H showing the signals at 2.2 ppm is a ¹ H showing the signals in the three, 3.9 ppm is 4, and the ¹ H signal indicating the signal at 7.2 ppm is 13. That is, ¹ H, which represents a signal at more than 3.5 ppm, is 17, which corresponds to 85% of the total number of ¹ H.

The insulating oil has a viscosity of 2 mm ² / s or higher at 20 to 30 ° C, and is not preferable because the insulating oil does not dissolve out of the insulating layer when the insulating oil has such a viscosity.

In the present invention, the weight ratio of the mixture (A) of the polypropylene and the ethylene-propylene copolymer to the insulating oil (B) is 100: 2.5 to 10 (A: B). When the amount of the insulating oil (B) is less than 2.5 parts by weight relative to 100 parts by weight of the mixture (A) of the polypropylene and the ethylene-propylene copolymer in relation to the above ratio, flexibility can not be imparted, (B) is used in an amount exceeding 10 parts by weight relative to 100 parts by weight of a mixture (A) of a polypropylene and an ethylene-propylene copolymer, there is a problem in that the dielectric oil is eluted during the extrusion process, Occurs.

[Example]

Hereinafter, the present invention will be described more specifically by way of examples. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims and their equivalents. It should not be construed as an intention to limit the scope to example.

≪ Examples and Comparative Examples 1 to 4 >

In order to examine the physical properties of the insulating layer according to the insulating oil of the present invention, an insulating layer was prepared with the composition shown in Table 1 below. The units in Table 1 are parts by weight.

Insulating layer component Example Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Polypropylene and
A mixture of ethylene-propylene copolymers 100 100 100 100 100 Dibenzyltoluene (DBT) 5 - - One 12 Dodecylbenzene (DDB) - 5 - - - 1,2-diphenylethane - - 5 - -

Dodecylbenzene (DDB), an insulating oil used in Comparative Example 1, is represented by the following Chemical Formula 2.

The total number of dodecyl benzene ¹ H of chamber 30 is, ¹ H nuclear magnetic resonance ⁽¹ H-NMR) spectra ¹ H when the signal shown in the 0.9 ~ 2.2 ppm showing a signal of ¹ in 25, 7.2ppm H is five. That is, ¹ H, which represents a signal at more than 3.5 ppm, is 5, which corresponds to about 17% of the total number of ¹ H.

The 1,2-diphenylethane used as the insulating oil used in Comparative Example 2 is as shown in the following Chemical Formula 3.

The ^{1,2-diphenyl-1,} and the total number of 14 of the H of ethane, ¹ H nuclear magnetic resonance ⁽¹ H-NMR) spectroscopic signals in a 2.0 ~ 2.5 ppm in the analysis is shown ¹ H 4, at 7.2ppm The signal ¹ H is 10. That is, ¹ H, which represents a signal at more than 3.5 ppm, is 10, which corresponds to about 71% of the total number of ¹ H.

Measurement and evaluation of physical properties

A cable including the insulating layer according to the above Examples and Comparative Examples 1 to 4 was produced by a conventional method. Mechanical properties (tensile strength and tensile elongation) at room temperature, mechanical properties after heating (tensile strength, elongation percentage), flexural strength and dielectric breakdown strength of the specimens of the examples and comparative examples thus obtained were evaluated by the methods described below. The evaluation results are shown in Table 2 below.

㉠ Room temperature mechanical properties

The cable shall have a tensile strength of 1.27 kgf / mm ² or more and a tensile elongation of 200% or more when measured at a tensile rate of 250 mm / min in accordance with IEC 60811-1-1.

기계 Mechanical properties after heating

The cable was heated and aged at 150 ° C for 168 hours, and mechanical properties were measured. At this time, the residual tensile strength and elongation shall be at least 75%.

㉢ Flexural strength

The flexural strength was measured according to IEC 60811-1-1 standard, and the lower the value, the better the cable laying performance.

㉣ Insulation breaking strength

The dielectric breakdown strength was measured according to ASTM D149 standard, and the higher the value, the better the electrical characteristics.

Example Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Tensile strength at room temperature (kgf / mm ² ) 2.0 1.8 2.0 2.05

Not measurable

Tensile elongation at room temperature (%) 698 705 680 680 Residual tensile strength after heating (%) 81 110 78 83 Renal survival rate after heating (%) 79 55 70 82 Flexural Strength (MPa) 30 25 29 41 Dielectric breakdown strength (kV / mm) 65 64 65 58

As summarized in Table 2, in the case of Comparative Example 1, the use of an insulating oil having a signal of not less than about 17% of the total number of ¹ H of ¹ H, which was signaled at not less than 3.5 ppm, resulted in a percent elongation after heating of only 55% This was not good.

Comparative Example 2 In the case of after an ¹ H showing a signal from more than 3.5 ppm is heated with use of only the insulating oil in about 71% of the total number of ¹ H renal survival rate was poor and the mechanical properties of only 70%.

In the case of Comparative Example 3, a small amount (1 part by weight) of insulating oil was used, so that the flexural strength of the cable was high. As a result, the cable of Comparative Example 3 has low flexibility and excellent cable laying performance can not be expected.

In the case of Comparative Example 4, since an excessive amount of insulating oil was used (12 parts by weight), dielectric oil was eluted during the extrusion process, and slipping occurred in the extruder. As a result, the cable could not be manufactured, and the above physical properties could not be measured.

On the other hand, in the case of the embodiment of the present invention, not only the mechanical properties after the heating and heating were excellent but also the flexibility of the cable was secured by using the suitable insulating oil.

As described above, the optimal embodiments of the present invention have been disclosed. Although specific terms have been employed in the specification to include those embodiments, it will be understood that they have been used only for the purpose of describing the invention to those of ordinary skill in the art and are intended to limit the scope of the invention as defined in the claims Or not.

1 denote the following.
11 ... Conductor
12 ... Inner semiconductive layer
13 ... Insulating layer
14 ... Outer semiconductive layer
15 ... Shielding layer
16 ... Sheath layer

Claims (3)

A cable comprising at least one conductor and an insulating layer surrounding the conductor,
Wherein the insulating layer is formed by extrusion of a mixture of polypropylene and ethylene-propylene copolymer and insulating oil,
The weight ratio of the mixture of polypropylene and ethylene-propylene copolymer to the insulating oil is 100: 2.5-10,
The insulating oil has a viscosity of 2 mm ² / s or more at 20 to 30 ° C. and has a viscosity of more than 80% of the total number of ¹ H signals in an area of not less than 3.5 ppm in ¹ H nuclear magnetic resonance ( ¹ H-NMR) Lt; / RTI > The method according to claim 1,
Wherein said dielectric oil comprises dibenzyltoluene. delete

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