JP2008234883A - Bridged polyethylene electric wire-cable and resin composition for insulator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bridged polyethylene electric wire-cable and a resin composition for an insulator, which restrains shrinking-back and improves a flexibility of material selection. <P>SOLUTION: In a bridged polyethylene cable 1, the insulator 3 for covering a conductor 2 is formed by a plurality of layers, and a lower layer 5 of the insulator 3 brought into contact with the conductor 2 is made of a resin composition for an insulator in which polyolefin, a radical generating agent, a silane compound, and a silanol condensation catalyst are combined with each other, wherein the polyolefin is a mixture of one or two components and more among low-density polyethylene, ethylene vinylacetate copolymer, ethylene ethylacrylate copolymer, and ethylene methylmethacrylate copolymer, and the polyolefin has a melting point of 90 to 110°C and a gel molar ratio of 10 to 40%, and a thickness of the lower layer 5 of 0.05 to 0.3 mm. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a crosslinked polyethylene electric wire / cable and an insulating resin composition used as an insulator of the crosslinked polyethylene electric wire / cable.

  It is known that a cross-linked polyethylene cable (or a cross-linked polyethylene electric wire) is excellent in electrical characteristics, mechanical characteristics, chemical characteristics, heat resistance, laying workability, and the like. Therefore, it has been widely used as a high voltage power cable. A crosslinked polyethylene cable employs a method of crosslinking a crosslinked polyethylene insulating coating layer (insulator) by water crosslinking because it does not require expensive crosslinking equipment.

  What is problematic in the water crosslinking method is the problem of large shrinkage of the polyethylene insulating coating layer that occurs during the extrusion and cooling processes. Specifically, when the silane crosslinkable polyethylene composition is extruded and coated as a thick uncrosslinked polyethylene insulating coating layer by an extruder, the uncrosslinked polyethylene insulating coating layer is greatly contracted in the length direction after the extrusion coating. Phenomenon (called shrinkback) occurs. This is a problem of large shrinkage of the polyethylene insulating coating layer generated during the extrusion and cooling processes.

  Since a thick-walled cross-linked polyethylene cable has a large amount of shrinkage, when it is subjected to a heat cycle during use, a protruding phenomenon occurs at the terminal. When this protrusion phenomenon occurs, the terminal is likely to be inundated, which causes a problem.

As for the above-mentioned problems, etc., as a technology of a crosslinked polyethylene electric wire / cable using the silane crosslinkable polyethylene composition obtained by blending two kinds of low density polyethylene having different crystallization temperatures as an insulating coating layer in the following Patent Document 1. It is disclosed. The conventional technology of Patent Document 1 can suppress shrinkback by adjusting the blend amount of the two types of low-density polyethylene.
JP 2001-126536 A

  In the prior art of Patent Document 1, although shrinkback can be suppressed, there is a problem that usable resin compositions for insulators are limited. In other words, there is a problem that the degree of freedom in material selection is reduced in order to suppress shrinkback.

  The present invention has been made in view of the above-described circumstances, and a crosslinked polyethylene electric wire / cable and insulator resin composition capable of both suppressing shrinkback and increasing the degree of freedom in material selection. It is an issue to provide.

  The cross-linked polyethylene electric wire / cable of the present invention according to claim 1, which has been made in order to solve the above-mentioned problems, comprises a plurality of insulators covering a conductor, and a lower layer of the insulator in contact with the conductor is a polyolefin or silane A resin composition for an insulator comprising a compound, a radical generator and a silanol condensation catalyst, wherein the polyolefin is a low density polyethylene, an ethylene vinyl acetate copolymer, an ethylene ethyl acrylate copolymer, an ethylene methyl methacrylate copolymer. The melting point is 90 to 110 ° C., the gel fraction is 10 to 40%, and the thickness of the lower layer is 0.05 to 0.3 mm. Yes.

  According to the present invention having such characteristics, it is possible to configure the insulator in a plurality of layers and to suppress shrink back by the resin composition in the lower layer of the insulator. Further, by configuring the insulator with a plurality of layers, the upper layer of the insulator can be formed of, for example, a general crosslinked polyethylene having high heat resistance. According to the present invention, the lower layer of the insulator is formed of the resin composition that increases the sliding resistance with the conductor. Moreover, the lower layer of an insulator is formed with the resin composition in consideration of heat deformation.

  In the present invention, the insulator has a two-layer structure or a three-layer structure. In the case of a three-layer structure, for example, if a resin having a poor appearance is used for the intermediate layer, a low-cost design can be achieved. The above four resins are the target of polyolefin, and these do not change regardless of which you choose side by side.

  The reason why the melting point of the polyolefin is set to 90 to 110 ° C. in the present invention is to increase the sliding resistance with the conductor. In addition, the melting point should be lower, and when used (upper limit 90 ° C: the electrical appliance method is designed to use 90 ° C. The cross-linked polyethylene cable has a heat deformation test temperature of 120 ° C. This is because safety (resin deformation, etc.) of the melting point of less than 90 ° C. is impossible regardless of the operating temperature.

  In the present invention, the gel fraction of the polyolefin is set to 10 to 40% in order to increase the sliding resistance with the outer layer in contact with the lower layer (upper limit value). Moreover, this is because the heat resistance is taken into consideration (lower limit value).

Examples of the resin applicable to the outer layer in the present invention include one or a mixture of two or more of low density polyethylene (LDPE), linear low density polyethylene (L-LDPE), and medium density polyethylene (MDPE). Shall be. Among the above resins, linear low density polyethylene (L-LDPE) is preferable in terms of heat resistance, and this is a preferable resin. In addition, although not particularly limited, a density of 0.930 g / mm ³ or less is preferable.

  The reason why the thickness of the lower layer is set to 0.05 to 0.3 mm in the present invention is that if it is less than 0.05 mm, the sliding resistance with the conductor is affected, which may cause shrinkback. Moreover, it is because there exists a possibility of affecting the heat resistance as a cable when it exceeds 0.3 mm.

  The resin composition for an insulator of the present invention according to claim 2, which has been made to solve the above-mentioned problems, comprises a polyolefin, a silane compound, a radical generator, and a silanol condensation catalyst, and comprises an insulator in contact with a conductor. A resin composition for insulator used as a lower layer, wherein the polyolefin is one or two components of low density polyethylene, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene methyl methacrylate copolymer The above mixture is characterized by a melting point of 90 to 110 ° C. and a gel fraction of 10 to 40%.

  According to the present invention having such a feature, the resin composition for an insulator is suitable as a lower layer of the insulator in contact with the conductor.

  According to the present invention described in claim 1, there is an effect that it is possible to provide a crosslinked polyethylene electric wire / cable that can both suppress shrinkback and increase the degree of freedom of material selection. Play.

  According to the second aspect of the present invention, there is provided a resin composition for an insulator capable of both suppressing shrinkback of a crosslinked polyethylene electric wire / cable and increasing the degree of freedom of material selection. There is an effect that can be.

  Hereinafter, description will be given with reference to the drawings. FIG. 1 is a cross-sectional view of a crosslinked polyethylene cable showing an embodiment of the present invention.

  In FIG. 1, a cross-linked polyethylene cable 1 of the present invention includes a conductor 2, an insulator 3 that is extruded to the outside of the conductor 2, and a sheath 4 that is further extruded to the outside of the insulator 3 to cover it. It is configured with. The insulator 3 has a two-layer structure of a lower layer 5 formed so as to be in contact with the conductor 2 and an upper layer 6 outside the lower layer 5.

  The lower layer 5 is formed by extruding this using the resin composition for insulator (lower resin composition) of the present invention. The lower layer 5 is formed with a thickness of 0.05 to 0.3 mm (this thickness is one of the characteristics of the present invention). The upper layer 6 is a general crosslinked polyethylene insulating layer having high heat resistance (detailed explanation is omitted). The insulator 3 can ensure electrical characteristics, mechanical characteristics, chemical characteristics, heat resistance, laying workability, and the like as in the prior art.

  The resin composition for an insulator (lower resin composition) to be the lower layer 5 is formed by blending a polyolefin, a silane compound, a radical generator, and a silanol condensation catalyst, and the polyolefin is a low density polyethylene, ethylene acetate. The melting point is 90 to 110 ° C. and the gel fraction is 10 to 40% in one or a mixture of two or more components among vinyl copolymer, ethylene ethyl acrylate copolymer and ethylene methyl methacrylate copolymer ( The melting point and gel fraction shall be one of the features of the present invention).

  The reason why the melting point is set to 90 to 110 ° C. is to increase the sliding resistance with the conductor 2 and to consider safety during use (deformation of the resin, etc.). The reason why the gel fraction is set to 10 to 40% is to increase the sliding resistance with the outer layer 6 in contact with the lower layer 5 (upper limit value) and to consider heat resistance (lower limit value).

  The reason why the thickness of the lower layer 5 is set to 0.05 to 0.3 mm is that if it is less than 0.05 mm, the sliding resistance with the conductor 2 is affected, and if it exceeds 0.3 mm, the heat resistance as a cable is increased. This is because it may affect sex.

  In such a crosslinked polyethylene cable 1 of the present invention, shrinkback can be satisfactorily suppressed without impairing heat resistance. In the cross-linked polyethylene cable 1, the insulator 3 has a two-layer structure (a three-layer structure is possible if the lower layer 5 is provided), so that the upper layer 6 has a higher degree of freedom in material selection than before. It can be significantly improved.

  Hereinafter, the insulator resin composition (lower resin composition) to be the lower layer 5 will be described in detail.

  When the compounding example of the resin composition for insulators (lower layer resin composition) used as the lower layer 5 is given, as shown in Table 1, the low density polyethylene as the polyolefin is 100 parts by weight (phr) as the silane compound. 0.5 to 1.5 parts by weight of vinyltrimethoxysilane, 0.02 to 0.15 parts by weight of dicumyl peroxide as a radical generator, and 0.05 to 0. 0 of dibutyltin diurarate as a silanol condensation catalyst. 3 parts by weight of tetrakis [methylene-3 (3.5-di-tert-butyl-4-hydroxy-phenyl) propionate] methane as an antioxidant is mixed in an amount of 0.05 to 0.3 parts by weight. Yes.

  As the low-density polyethylene, for example, Ultzex manufactured by Mitsui Chemicals, Inc. is used. As the vinyltrimethoxysilane, KBM1003 manufactured by Shin-Etsu Chemical Co., Ltd. is used, for example. As the dicumyl peroxide, Mitsui DCP manufactured by Mitsui Petrochemical Co., Ltd. is used, for example. As the dibutyltin dilaurate, for example, BT-11 manufactured by Asahi Denka Kogyo Co., Ltd. is used. Further, as the tetrakis [methylene-3 (3.5-di-tert-butyl-4-hydroxy-phenyl) propionate] methane, for example, Irganox 1010 manufactured by Ciba Specialty Chemicals Co., Ltd. is used. .

  Specific examples of the present invention will be described, and examples and comparative examples will be compared. Examples 1 to 3 and Comparative Examples 1 to 4 are manufactured with the configuration of the crosslinked polyethylene cable 1 and are compared. Regarding the blending of the resin composition for insulator (lower layer resin composition) to be the lower layer 5, it is based on the blending of Table 1. First, refer to Table 1 and Table 2.

Example 1
Example 1 is an insulation formed by extruding a resin composition for an insulator (lower layer resin composition) containing a low-density polyethylene having a melting point of 95 ° C. and a gel fraction of 15% as described above to a conductor and then water-crosslinking it. A cross-linked polyethylene cable having a lower body layer. The upper layer of the insulator is made of general crosslinked polyethylene having high heat resistance.

Example 2
Example 2 is an insulation formed by extruding a resin composition for an insulator (lower layer resin composition) containing low-density polyethylene having a melting point of 95 ° C. and a gel fraction of 25% as described above, and then water-crosslinking the conductor. A cross-linked polyethylene cable having a lower body layer. The upper layer of the insulator is made of general crosslinked polyethylene having high heat resistance.

Example 3
Example 3 is an insulating material obtained by extruding a conductor resin composition (underlayer resin composition) containing low-density polyethylene having a melting point of 105 ° C. and a gel fraction of 35% as described above to a conductor and then water-crosslinking the conductor composition. A cross-linked polyethylene cable having a lower body layer. The upper layer of the insulator is made of general crosslinked polyethylene having high heat resistance.

Comparative Example 1
Comparative Example 1 is an insulation formed by extruding a resin composition for an insulator (lower layer resin composition) in which a low-density polyethylene having a melting point of 85 ° C. and a gel fraction of 25% is blended as described above onto a conductor and then water-crosslinking A cross-linked polyethylene cable having a lower body layer. The upper layer of the insulator is made of general crosslinked polyethylene having high heat resistance.

Comparative Example 2
Comparative Example 2 is an insulation formed by extruding a resin composition for an insulator (lower layer resin composition) containing a low-density polyethylene having a melting point of 125 ° C. and a gel fraction of 25% as described above, and then water-crosslinking the conductor composition. A cross-linked polyethylene cable having a lower body layer. The upper layer of the insulator is made of general crosslinked polyethylene having high heat resistance.

Comparative Example 3
Comparative Example 3 is an insulation formed by extruding a resin composition for an insulator (underlayer resin composition) containing a low-density polyethylene having a melting point of 125 ° C. and a gel fraction of 15% as described above to a conductor and then water-crosslinking it. A cross-linked polyethylene cable having a lower body layer. The upper layer of the insulator is made of general crosslinked polyethylene having high heat resistance.

Comparative Example 4
Comparative Example 4 is an insulation formed by extruding a resin composition for an insulator (lower layer resin composition) containing a low-density polyethylene having a melting point of 115 ° C. and a gel fraction of 45% as described above, and then water-crosslinking the conductor. A cross-linked polyethylene cable having a lower body layer. The upper layer of the insulator is made of general crosslinked polyethylene having high heat resistance.

  As comparative evaluation with Examples 1-3 and Comparative Examples 1-4, each test which concerns on shrinkback and heat resistance (heat deformation) is implemented and evaluated.

  The test related to shrinkback is specified in IEC60881-1-3, and as the test, the shrinkage rate is calculated by measuring the distance between marked lines before and after heating at 130 ° C. for 1 hour. The shrinkage rate is the same as shrinkback (shrinkback amount), and the calculation formula is shrinkback amount = (distance between marked lines before heating−distance between marked lines after heating) / distance between marked lines before heating. * Expressed in 100 (%). For shrinkback, this standard is 4% or less, but here, if it is 2% or less, it will be judged as “Good”, and if it exceeds 2%, it will be judged as “No” if it is rejected. .

  The test relating to heat resistance (heating deformation) shall be conducted according to Japanese Industrial Standard JIS C 3005 (specified by the deformation ratio before and after heating at 120 ° C. for 1 hour). As for heat resistance (heat deformation), the standard of heat deformation rate is 40% or less, but here it is “○” when it is 30% or less, and “X” when it exceeds 30% other than this. Shall be determined.

  In the evaluation, “◯” is evaluated as a good result when both of the above-described shrinkback and heat resistance (heat deformation) tests are passed, and “x” is evaluated in other cases.

  According to the evaluation results in Table 2, in Examples 1 to 3 relating to the present invention, the determination of shrinkback and heat resistance (heat deformation) is all passed, and a good result of evaluation “◯” is obtained. On the other hand, in Comparative Examples 1 to 4, the determination of heat resistance (heating deformation) is unsuccessful, or the determination of shrinkback is unsuccessful, and the result is an evaluation of “×”.

  When analyzing Comparative Examples 1 to 4, first, Comparative Example 1 has a melting point of 85 ° C. which does not fall within the range of 90 to 110 ° C., which is a feature of the present invention. It is a pass and the result is an evaluation of “×”. Next, since the comparative example 2 and the comparative example 3 are 125 degreeC whose melting | fusing point does not enter into the range of 90-110 degreeC which is the characteristics of this invention, determination of shrinkback is unacceptable. It has been evaluated. Finally, in Comparative Example 4, the melting point is 115 ° C. which does not fall within the range of 90 to 110 ° C., which is a feature of the present invention, and the gel fraction does not fall within the range of 10 to 40% which is a feature of the present invention. Since it is 45%, the shrinkback determination is unacceptable, and as a result, the evaluation is “×”.

  Subsequently, referring to Table 3, the example and the comparative example are further compared. Both Examples 4 and 5 and Comparative Examples 5 and 6 are manufactured with the configuration of the crosslinked polyethylene cable 1 and are compared by changing the thickness of the lower layer 5. Regarding the blending of the resin composition for insulator (lower layer resin composition) to be the lower layer 5, it is based on the blending of Table 1.

Example 4
Example 4 is an insulating material obtained by extruding a conductor resin composition (underlayer resin composition) containing low-density polyethylene having a melting point of 95 ° C. and a gel fraction of 15% as described above onto a conductor and then water-crosslinking the resin composition. A cross-linked polyethylene cable having a lower body layer. The thickness of the lower layer is 0.10 mm. The upper layer of the insulator is made of general crosslinked polyethylene having high heat resistance.

Example 5
Example 5 is an insulating material obtained by extruding a conductor resin composition (lower layer resin composition) containing low-density polyethylene having a melting point of 95 ° C. and a gel fraction of 15% as described above to a conductor and then water-crosslinking the conductor composition. A cross-linked polyethylene cable having a lower body layer. The thickness of the lower layer is 0.25 mm. The upper layer of the insulator is made of general crosslinked polyethylene having high heat resistance.

Comparative Example 5
Comparative Example 5 is an insulation formed by extruding a resin composition for an insulator (lower layer resin composition) in which a low-density polyethylene having a melting point of 95 ° C. and a gel fraction of 15% as described above is extruded onto a conductor and then water-crosslinking. A cross-linked polyethylene cable having a lower body layer. The thickness of the lower layer is 0.03 mm. The upper layer of the insulator is made of general crosslinked polyethylene having high heat resistance.

Comparative Example 6
Comparative Example 6 is an insulation formed by extruding a resin composition for an insulator (lower layer resin composition) containing a low-density polyethylene having a melting point of 95 ° C. and a gel fraction of 15% as described above to a conductor and then water-crosslinking it. A cross-linked polyethylene cable having a lower body layer. The thickness of the lower layer is 0.35 mm. The upper layer of the insulator is made of general crosslinked polyethylene having high heat resistance.

  As a comparative evaluation between Examples 4 and 5 and Comparative Examples 5 and 6 in which the thickness of the lower layer is changed, each test relating to the above shrinkback and heat resistance (heat deformation) is performed and evaluated.

  According to the evaluation results in Table 3, in Examples 4 and 5 relating to the present invention, the determination of shrink back and heat resistance (heat deformation) is all passed, and a favorable result of “◯” is obtained. On the other hand, in Comparative Examples 5 and 6, the determination of shrinkback is unsuccessful, or the determination of heat resistance (heat deformation) is unsuccessful, and as a result, the evaluation is “×”.

  Analysis of Comparative Examples 5 and 6 shows that the melting point is in the range of 90 to 110 ° C., which is a feature of the present invention, and the gel fraction is also in the range of 10 to 40%, which is a feature of the present invention. × ”rating. This is due to the influence of the thickness of the lower layer, and if the thickness of the lower layer is less than 0.05 mm, the slip resistance with the conductor is affected, which makes the shrinkback determination unacceptable. Moreover, if the thickness of the lower layer exceeds 0.3 mm, the heat resistance of the cable may be affected, and this makes the determination of heat resistance (heat deformation) unacceptable. Therefore, it can be seen from such analysis that the thickness of the lower layer is an important feature of the present invention in addition to the melting point and gel fraction.

  As described above, in the crosslinked polyethylene cable 1 of the present invention, the insulator 3 covering the conductor 2 is composed of a plurality of layers, and the lower layer 5 of the insulator 3 in contact with the conductor 2 is made of polyolefin, silane compound, radical generator, silanol condensation catalyst. It comprises a resin composition for insulators, and is a mixture of one or two or more components of low density polyethylene, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, and ethylene methyl methacrylate copolymer. The melting point is 90 to 110 ° C., the gel fraction is 10 to 40%, and the thickness of the lower layer 5 is 0.05 to 0.3 mm, so that shrinkback can be suppressed. In addition, there is an effect that the degree of freedom of material selection can be increased (in addition, the above description is a bridge including the sheath 4). Was the description of triethylene cable 1, insulated wire without the sheath 4, namely to achieve the same effect as described above a cross-linked polyethylene cable (not shown) of course).

  In addition, it goes without saying that the present invention can be variously modified without departing from the spirit of the present invention.

It is sectional drawing of the bridge | crosslinking polyethylene cable which shows one embodiment of this invention.

Explanation of symbols

1 Cross-linked polyethylene cable 2 Conductor 3 Insulator 4 Sheath 5 Lower layer 6 Upper layer

Claims (2)

The insulator covering the conductor is composed of a plurality of layers, and the lower layer of the insulator in contact with the conductor is composed of a resin composition for an insulator formed by blending a polyolefin, a silane compound, a radical generator, and a silanol condensation catalyst, Polyolefin is low density polyethylene, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene methyl methacrylate copolymer, or a mixture of two or more components, melting point 90-110 ° C., gel fraction 10 It is -40%, Furthermore, the thickness of the said lower layer will be 0.05-0.3 mm. The bridge | crosslinking polyethylene electric wire and cable characterized by the above-mentioned. A resin composition for an insulator comprising a polyolefin, a silane compound, a radical generator, a silanol condensation catalyst, and used as a lower layer of an insulator in contact with a conductor,
The polyolefin is one or a mixture of two or more of low density polyethylene, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene methyl methacrylate copolymer, and has a melting point of 90 to 110 ° C. and a gel fraction. 10 to 40% of the resin composition for an insulator, characterized in that

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