KR20120095240A - Cable including insulation layer with insulating oil - Google Patents

Abstract

PURPOSE: A cable is provided to comprise excellent flexibility by comprising an insulating layer containing a non-crosslinked resin. CONSTITUTION: A cable comprises at least one conductor(11), and an insulating layer(13) surrounding the conductor. The insulating layer comprises a mixture of polypropylene and ethylene-propylene copolymers, and insulating oil. The insulating oil has a signal in region where 80% of total 1H number is 3.5 ppm or more at 1H nuclear magnetic resonance(1H-NMR) spectrum analysis. The insulating oil has viscosity of 2 mm^2/s or more at 20-30 °C. The weight ratio of the mixture of polypropylene and ethylene-propylene copolymers and the insulating oil is 100:2.5-10.

Description

Cable Including Insulation Layer With Insulating Oil

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

Commonly used cables include a conductor 11, an inner semiconducting layer 12, an insulating layer 13, an outer semiconducting layer 14, a shielding layer 15 and a sheath layer 16, as shown in FIG. It may have a structure including. In order to satisfy the high tensile strength mechanical properties required by the cable standard, the prior art used cross-linked polyethylene as a component constituting the insulating layer (13). However, due to the high crystallinity of the crosslinked polyethylene, the flexural strength is high at room temperature, and when applied as an insulator of the cable, flexibility of the cable cannot be secured. This caused difficulties in laying work in the field, and required a lot of force especially when bending to install the cable in a narrow space. Accordingly, more effort and technology are required to install the cable, and the installation cost is high, resulting in a problem in that the productivity is lowered.

Therefore, there is a need for the development of a flexible cable including an insulating layer manufactured without using a crosslinked resin.

An object of this invention is to provide the cable excellent in flexibility, including the insulating layer containing a non-crosslinking resin.

The present invention for achieving the above object relates to a cable comprising at least one conductor and an insulating layer surrounding the conductor, the insulating layer comprises a mixture of polypropylene and ethylene-propylene copolymer and insulating oil, the insulating oil In ¹ H nuclear magnetic resonance ( ¹ H-NMR) spectroscopic analysis, characterized in that more than 80% of the total number of ¹ H signal in the region of 3.5 ppm or more.

Since the cable of the present invention does not use the crosslinked polyethylene, which is used as a component of the insulating layer, the cost increase due to the crosslinking process and the problems of deterioration of the insulation performance due to the crosslinking by-products do not occur. Therefore, the cable can be easily installed by increasing the cable flexibility.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings attached to the present specification illustrate exemplary embodiments of the present invention, and together with the detailed description of the present invention, the present invention is intended to help understand the technical idea of the present invention. No.
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 ethylene-propylene copolymer and insulating oil. In the present invention, since the flexibility of the cable can be increased by using insulating oil, the cable laying property can be improved.

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 signal in the region of 3.5 ppm or more. The use of insulating oils, which exhibit signals in this area, is advantageous because the cables produced have excellent mechanical properties. Dibenzyl toluene (DBT) which has a following formula as an example of such insulating oil is mentioned.

The total number of ¹ H of dibenzyltoluene is 20, ¹ H signal at 2.2 ppm in ¹ H nuclear magnetic resonance ( ¹ H-NMR) spectroscopic analysis, 3 ¹ H signal at 3.9 ppm, ¹ H is signal 4, ¹ H showing the signals at 7.2ppm the dog 13. In other words, ¹ H showing a signal from more than 3.5 ppm is equivalent to 85% of the total number of H ¹ as 17.

The insulating oil has a viscosity of 2 mm ² / s or more at 20 ~ 30 ℃, it is preferable because the phenomenon that the insulating oil is eluted from the insulating layer does not appear when the insulating oil has such a viscosity.

In the present invention, the weight ratio of the mixture (A) and the insulating oil (B) of the polypropylene and ethylene-propylene copolymer is 100: 2.5 to 10 (A: B). Regarding the above ratio, when the insulating oil (B) is used in an amount less than 2.5 parts by weight relative to 100 parts by weight of the mixture (A) of polypropylene and ethylene-propylene copolymer, it is difficult to lay the cable because the flexibility cannot be given. When the insulating oil (B) is used in an amount of more than 10 parts by weight based on 100 parts by weight of the mixture (A) of polypropylene and ethylene-propylene copolymer, the insulating oil is eluted during the extrusion process, which makes it difficult to process the cable. 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 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.

Insulation layer Example Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 With polypropylene
Mixture of ethylene-propylene copolymers 100 100 100 100 100 Dibenzyltoluene (DBT) 5 - - One 12 Dodecylbenzene (DDB) - 5 - - - 1,2-diphenylethane - - 5 - -

Dodecylbenzene (DDB) which is an insulating oil used in Comparative Example 1 is as shown in the following 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 that signaled more than 3.5 ppm is 5, corresponding to about 17% of the total number of ¹ H.

1,2-diphenylethane as an insulating oil used in Comparative Example 2 is as shown in the following 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 ¹ H shows a signal 10 atoms. In other words, ¹ H showing a signal from more than 3.5 ppm corresponds to about 71% ^of the total number H as 10.

Measurement and evaluation of physical properties

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

㉠ Mechanical properties at room temperature

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

기계적 Mechanical properties after heating

The mechanical properties of the cables were measured after heat aging at 150 ° C. for 168 hours. At this time, the tensile strength residual ratio and elongation residual ratio should be at least 75%.

강도 flexural strength

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

㉣ dielectric breakdown strength

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

Example Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Room temperature tensile strength (kgf / mm ² ) 2.0 1.8 2.0 2.05

Not measurable

Room Temperature Tensile Elongation (%) 698 705 680 680 Tensile strength residual after heating (%) 81 110 78 83 Residual elongation after heating (%) 79 55 70 82 Flexural Strength (MPa) 30 25 29 41 Insulation breakdown strength (kV / mm) 65 64 65 58

As shown in Table 2, Comparative Example 1 After the ¹ H showing a signal from more than 3.5 ppm is heated in accordance with the use of the insulating oils of only about 17% of the total number of ¹ H by renal survival rate of only 55% of the mechanical properties For the 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, the bending strength of the cable was high by using a small amount (1 part by weight) of insulating oil. For this reason, the cable of the comparative example 3 is low in flexibility and cannot expect the outstanding cable laying property.

In Comparative Example 4, as the insulating oil was used in an excessive amount (12 parts by weight), the insulating oil was eluted during the extrusion process, thereby causing a sliding phenomenon in the extruder. As a result, a cable could not be manufactured and said physical property measurement was not possible.

On the other hand, in the embodiment of the present invention, not only the mechanical properties after room temperature and heating were excellent, but also the flexibility of the cable could be secured by using an appropriate insulating oil.

As described above, optimal embodiments of the present invention have been disclosed. Although specific terms have been used in the specification including the present embodiment, it is only used for the purpose of describing the present invention to those skilled in the art in detail and used to limit the meaning or limit the scope of the present invention described in the claims. Make it clear.

The symbol shown in FIG. 1 means the following.
11 ... Conductor
12 ... Inner semiconducting layer
13 ... Insulating layer
14. Outer semiconducting layer
15 ... Shielding layer
16. Sheath layer

Claims (3)

A cable comprising at least one conductor and an insulation 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) is at least 80% of the total number of ¹ H, when spectroscopy or more 3.5 ppm A cable characterized by representing a signal in an area. The method of claim 1,
The insulating oil has a viscosity of 2 mm ² / s or more at 20 ~ 30 ℃ cable. The method of claim 1,
The weight ratio of the mixture of the polypropylene and ethylene-propylene copolymer and the insulating oil is 100: 2.5 to 10 cable.

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