JPH10116521A - Fluoro-rubber covered wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluoro-rubber covered wire having excellent surface appearance, and further having high mechanical strength and an excellent electric characteristic even in high temperature environment. SOLUTION: This fluoro-rubber covered wire is formed out of a conductor 1 having outer surface covered with an extrusion molded cover layer 3 of a fluoro-rubber composition composed by blending 100 pts.wt. of a tetrafluoroethylene-propylene copalymer with 20 to 40 pts.wt. of calcinated clay, 5 to 20 pts.wt. of MT carbon, 0.5 to 2 pts.wt. of organic peroxide, and 5 to 10 pts.wt. of a multi-allyl compound. Also, the cover layer 3 is cross-linked.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved coated electric wire having excellent heat resistance.

[0002]

2. Description of the Related Art Inexpensive chloroprene and chlorosulfonated polyethylene are widely used as covering materials for electric wires. However, due to insufficient heat resistance, the temperature in a high temperature environment, for example, a continuous use environment temperature exceeds 100 ° C. In such an environment, fluorine rubber having excellent heat resistance is used. Fluororubber, for example, tetrafluoroethylene-propylene copolymer, is a fluorine-containing elastomer having a high degree of thermal stability, and is particularly excellent in heat resistance by extrusion-coating this copolymer on the outside of a conductor and crosslinking. An electric wire can be obtained.

[0003]

However, since the tetrafluoroethylene-propylene copolymer has a high viscosity, it is inferior in processability when extrusion-coated on a conductor, resulting in poor electric wire appearance or thin wall. There were various disadvantages such as difficulty in coating. In addition, there is a problem that the mechanical strength and the electrical characteristics are lowered when trying to improve the processability.

An object of the present invention is to provide a fluorine rubber-coated electric wire having a good surface appearance and excellent mechanical strength and electric characteristics even in a high temperature environment.

[0005]

In order to achieve the above object, in the present invention, 20 to 40 parts by weight of a calcined clay is added to the outside of a conductor with respect to 100 parts by weight of a tetrafluoroethylene-propylene copolymer. Part, MT carbon 5
An extruded coating layer comprising a fluororubber composition comprising about 20 to 20 parts by weight, 0.5 to 2 parts by weight of an organic peroxide, and 5 to 10 parts by weight of a polyallyl compound. A coated wire is provided, wherein the layers are crosslinked.

[0006]

Embodiments of the present invention will be described below. FIG. 1 is a schematic cross-sectional view showing one embodiment of a coated electric wire of the present invention, in which an inner conductive layer 2 made of a semiconductive polyester tape is coated on a conductor 1 by extrusion coating with a fluororubber composition. The coating layers 3 are provided in this order. In FIG. 1, the extruded coating layer 3 is provided on the conductor 1 via the internal conductive layer 2, but the extruded coating layer 3 may be provided directly on the conductor 1 as shown in FIG. Also, a sheath 4 made of fluoro rubber or the like may be provided on the extruded coating layer 3 mainly in consideration of heat resistance. Alternatively, as shown in FIG. 3, a cable in which a plurality of insulated wires each having an extruded coating layer 3 provided on a conductor are twisted, and an intervening member 5 made of glass fiber or the like is provided and covered with a sheath 4 may be used.

The tetrafluoroethylene-propylene copolymer used as the base resin of the fluororubber composition in the present invention is a copolymer of tetrafluoroethylene and propylene. The molar ratio of tetrafluoroethylene / propylene is 95/5 to 30/70 mol%, preferably 90/10 to 45/55 mol%. In addition to the main components tetrafluoroethylene and propylene, components copolymerizable therewith, for example, ethylene, butene-1,
Isobutene, acrylic acid and its alkyl ester, methacrylic acid and its alkyl ester, vinyl fluoride,
It may contain vinylidene fluoride, hexafluoropropene, chloroethyl vinyl ether, glycidyl vinyl ether, chlorotrifluoroethylene, perfluoroalkyl vinyl ether or the like. Commercially available tetrafluoroethylene-propylene-based copolymers include AFLAS manufactured by Nippon Synthetic Rubber Co., Ltd., taking into account the required properties of electric wires such as flexibility, and appropriately selecting from various grades of commercially available products. A single compound or a mixture of several compounds can be used.

Further, since the fluororubber composition of the present invention contains calcined clay (Al ₂ O ₃ .2SiO ₂ ), it has excellent workability when extruded on a conductor and has excellent electrical characteristics. It will be particularly excellent. Talc has inferior electrical properties, and the addition of silica causes problems such as an increase in base resin viscosity and a decrease in electrical properties. The compounding amount is 20 to 40 parts by weight, particularly preferably 30 to 40 parts by weight, based on 100 parts by weight of the base resin. If the amount is less than 20 parts by weight, the moldability of the coating layer is inferior. If the amount exceeds 40 parts by weight, mechanical strength such as tensile strength and heat resistance are reduced.

Further, the fluororubber composition of the present invention comprises:
MT carbon is 5 to 100 parts by weight of the base resin.
20 parts by weight, preferably 5 to 10 parts by weight are blended. M
When T carbon is blended in the blending amount in this range, the moldability of the coating layer is improved. If the amount is too large, the electrical properties are adversely affected.

It is essential that the resin of the coating layer of the present invention is crosslinked, and a crosslinking agent is blended in the fluororubber composition. As the cross-linking agent, an organic peroxide can be suitably used. For example, dicumyl peroxide, 2,5-
Dimethyl-2,5-di (t-butylperoxide) hexine, 1,3-bis- (t-butylperoxyisopropyl) benzene, 1,1-di-t-butylperoxy-
3,3,5-trimethylcyclohexane and the like. The amount is based on 100 parts by weight of the base resin.
0.5 to 2 parts by weight is suitable.

Further, a polyallyl compound is compounded in the fluororubber composition as a crosslinking aid. Examples of the polyallyl compound include diallyl phthalate, triallyl dianurate, triallyl isocyanurate, diallyl melamine and the like, and preferably triallyl isocyanurate can be used. The compounding amount is suitably 5 to 10 parts by weight based on 100 parts by weight of the base resin.

The fluororubber-coated electric wire of the present invention is excellent in heat resistance because the resin of the coating layer is crosslinked. As a method for crosslinking the coating layer, after extruding the fluororubber composition on the outside of the conductor, 190 to 220
It is common to crosslink by heating at a temperature of ° C.

In addition, the fluororubber composition may further contain various additives used in the wire coating layer, such as a flame retardant, a coloring agent, a lubricant such as wax, an antioxidant, and the like. Can be appropriately compounded within a range that does not impair.

[0014]

EXAMPLE A cylinder (8 mm diameter, 0.8 mm outer diameter) was extruded using an extruder (15 mmφ, L / D = 13).
The fluororubber composition shown in Table 1 was extrusion-coated so as to have an outer diameter of 1.6 mmφ under the conditions of 5 ° C and a head of 90 ° C to obtain coated electric wires of Examples 1 to 6. The fluororubber compositions shown in Table 2 were extrusion-coated under the same conditions as in Examples 1 to 6,
The coated electric wires of Comparative Examples 1 to 7 were obtained by crosslinking.

For each of the obtained coated electric wires, various characteristics were measured and evaluated by the following test methods. 1) Surface appearance The appearance of the electric wire surface was observed according to the following criteria. ◎: The surface of the coating layer is smooth and glossy. ：: The surface of the coating layer is smooth. ：: Part of the surface of the coating layer is uneven or bumpy. ×: The entire surface of the coating layer is uneven or bumpy. Is

2) Tensile strength and elongation The resin composition prepared by mixing the components shown in Tables 1 and 2 with an 8-inch roll machine at 40 to 60 ° C. for 20 minutes to form a sheet, and then forming the sheet at 170 ° C. For 20 minutes to prepare a test sheet. JIS using this test sheet
K 6301 (Vulcanized rubber physical test method, tensile test JI
Tensile strength and elongation were measured according to S3 dumbbell).

3) Hardness The hardness was measured in accordance with JIS K 6301 (Vulcanized rubber physical test method, hardness test A type).

4) Degree of aging of elongation The residual elongation (%) of the test sheet is measured according to JIS K 6301 (Vulcanized rubber physical test method, aging test, air aging test (220 ° C., 96 hours)). did.

5) Volume resistivity Using a test sheet of 1 × 160 × 160 mm, JIS
It measured based on C2123 (Section 16).

6) AC Breakdown Voltage A conductive paint is applied to the dotted-lined concave portion of the test piece having the shape shown in FIG. 4 prepared from the test sheet, and a spherical electrode having a diameter of 12 mm is placed in the concave portion for 10 minutes. Each time, the applied voltage was raised by 1 kV, and the voltage up to dielectric breakdown was measured. In addition, using a test piece immersed in pure water at 80 ° C. for 7 days, a voltage until dielectric breakdown was measured in the same manner.

[0021]

[Table 1]

[0022]

[Table 2]

From the results shown in Table 1, all of the coated electric wires of Examples 1 to 6 using a crosslinked product of a specific resin composition containing a tetrafluoroethylene-propylene-based copolymer as a base resin as the coating layer are shown. It is clear that the electrical properties and the mechanical strength are excellent even after the heating test. On the other hand, in Comparative Example 1, since the compounded amount of the calcined clay was less than the specified amount in the present invention, the surface appearance of the electric wire was poor. In Comparative Example 2, since the blending amount of the calcined clay exceeds the prescribed amount, the residual elongation after heating is small. Comparative Example 3 is inferior in volume resistivity and low in AC breakdown voltage after hot water immersion because talc is blended in place of calcined clay. Comparative Example 4 has a low volume resistivity and a low AC breakdown voltage after immersion in hot water because silica is mixed in place of the calcined clay. Comparative Example 5 is inferior in tensile strength due to a large amount of MT carbon, has a low residual elongation after heating, a small volume resistivity, and a small AC breakdown voltage. In Comparative Example 6, since the amount of MT carbon was small, the appearance of the electric wire surface was inferior. In Comparative Example 7, the appearance of the electric wire surface was inferior because the fired clay was not blended.

[0024]

The fluororubber-coated electric wire of the present invention has a coating layer formed by extrusion molding of a specific fluororubber composition, and the coating layer is crosslinked, so that the surface appearance is reduced. It has good mechanical strength and excellent electrical properties, and can be suitably used even in a high-temperature environment.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a coated electric wire of the present invention.

FIG. 2 is a schematic sectional view showing another embodiment of the coated electric wire of the present invention.

FIG. 3 is a schematic sectional view showing another embodiment of the coated electric wire of the present invention.

FIG. 4 is an explanatory view showing a test piece used for measuring an AC breakdown voltage.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conductor 2 Internal conductive layer 3 Extrusion coating layer 4 Sheath 5 Interposition

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[Procedure amendment]

[Submission date] April 8, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction contents]

[0021]

[Table 1]

Claims (1)

[Claims] 1. An outside of a conductor, 20 to 40 parts by weight of calcined clay, 5 to 20 parts by weight of MT carbon, and 0 to 100 parts by weight of a tetrafluoroethylene-propylene copolymer based on 100 parts by weight of a tetrafluoroethylene-propylene copolymer. 0.5 to 2 parts by weight and 5 to 10 parts by weight of a polyallyl compound to form an extruded coating layer comprising a fluororubber composition, and the coating layer is crosslinked. Fluororubber-coated electric wire.