JPH10334736A - Wire/cable covered with elastomer containing fluorine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the tensile strength and elongation and improve the breakdown voltage and thermal aging resistance by mixing a specified amount of a silica-surface treated calcium carbonate to a fluorine polymer composition for covering a conductor or insulated wire core periphery. SOLUTION: An insulating wire core 3 obtained by stranding two crosslinked polyethylene insulated wires covered with crosslinked polyethylene is provided on the copper stranded wire 1, and the periphery is covered with a fluorine polymer composition. It is passed in an ionizing radiation irradiating rector and crosslinked by irradiating electron beams thereto, whereby a fluorine- containing elastomer covered wire or cable is provided. The fluorine polymer composition is obtained by mixing 5-100 wt.% of silica-surface treated calcium carbonate to 100 wt.% of a fluorine polymer. The initial tensile strength and elongation are enhanced, the tensile strength and elongation after thermal aging are enhanced, and the breakdown voltage is also increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorine-containing elastomer-coated electric wire / cable.

[0002]

2. Description of the Related Art Various rubbers and plastics are used as covering materials for electric wires and cables.

[0003] Rubber coating materials include natural rubber, chloroprene rubber, styrene butadiene rubber, chlorosulfonated polypolyethylene rubber, ethylene propylene diene rubber, polyurethane rubber, silicone rubber, fluorine rubber, and tetrafluoroethylene-propylene copolymer. .

As plastics coating materials, polyethylene, polypropylene, polyvinyl chloride admixture,
There are polyamide resin, fluorine resin and the like.

Among these, tetrafluoroethylene-propylene copolymers are excellent in flexibility, heat resistance, heat stability, electrical insulation, oil resistance, chemical resistance, flame retardancy, etc. -It has come to be widely used as a heat-resistant coating material for cables. In particular, a tetrafluoroethylene-propylene copolymer elastomer crosslinked by heat or radiation irradiation using peroxide is used for electric wires and
It is widely used as a heat-resistant coating material for cables.

However, since the tetrafluoroethylene-propylene copolymer also has plastic properties on one side, there is a problem that it is easily softened at high temperatures.
In particular, an electric wire formed by thinly coating a tetrafluoroethylene-propylene copolymer on a conductor or an outer periphery of an electric wire core.
Because the cable is thin, it is extremely susceptible to thermal softening at high temperatures.

[0007] The characteristic that it is difficult to thermally soften at such a high temperature is
It is evaluated for cut-through resistance. Although the details of this test method will be described later, the point is that a blade with a load is placed on the surface of the test material at a high temperature and the cut-through state is evaluated.

Hitherto, as a method for improving the cut-through resistance of a tetrafluoroethylene-propylene copolymer, a large amount of an inorganic filler has been used. Tetrafluoroethylene containing a large amount of such an inorganic filler
Propylene copolymer improves cut-through resistance,
There was a drawback that tensile strength, elongation, dielectric breakdown voltage, and heat aging resistance were significantly reduced.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of such a point, and an object of the present invention is to solve the above-mentioned disadvantages of the prior art and to provide a remarkably excellent cut-through resistance. An object of the present invention is to provide a fluorine-containing elastomer-coated electric wire / cable which is excellent in tensile strength, elongation, dielectric breakdown voltage and heat aging resistance.

[0010]

SUMMARY OF THE INVENTION The gist of the present invention is to provide a fluoroelastomer-coated electric wire or cable comprising a conductor or an outer periphery of an insulated electric wire core coated with a fluoropolymer composition. The composition is obtained by mixing 5 to 100 parts by weight of silica surface-treated calcium carbonate with 100 parts by weight of a fluorine-based polymer.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention of a fluorine-containing elastomer-coated electric wire / cable of the present invention will be described.

In the present invention, the fluoropolymer may be a tetrafluoroethylene-propylene copolymer, an ethylene-tetrafluoroethylene copolymer, or a tetrafluoroethylene-propylene copolymer having excellent heat resistance and flexibility. It is a blended fluorine polymer with an ethylene-tetrafluoroethylene copolymer.

Here, the blended fluoropolymer of the tetrafluoroethylene-propylene copolymer and the ethylene-tetrafluoroethylene copolymer does not limit the blend ratio, but from the viewpoint of the property balance, the tetrafluoroethylene-propylene copolymer is not preferred. A propylene copolymer and an ethylene-tetrafluoroethylene copolymer are mixed at a weight ratio of 95 /
A blend of 5-60 / 40 is suitable.

In the present invention, calcium carbonate was selected as a filler which does not decrease the heat resistance even when incorporated in a large amount into the fluoropolymer. Further, the present inventors blended the calcium carbonate as it is with a fluoropolymer, so that a diameter of 10
It has been discovered that giant secondary aggregates such as 〜30 μm are formed, and as a result, the electrical properties, particularly the dielectric breakdown voltage, are reduced.

The inventors of the present invention have conducted intensive studies on a method for solving the above-mentioned adverse effects when calcium carbonate is blended with a fluoropolymer. Was significantly improved, and thereby the generation of huge secondary aggregates could be suppressed.

As a method for producing such a silica surface-treated calcium carbonate, a one-stage dispersion polymerization method (for example, Hamakawa Paper Co., Ltd .; JP-A-6-102681) is known.

In the present invention, when the particle size of calcium carbonate is set to 10 μm or less, the dispersibility can be further improved. A practically preferable particle size range is 0.4 to 8 μm. In the present invention, the dielectric breakdown voltage can be significantly improved by discarding such special calcium carbonate.

In the present invention, the compounding amount of the silica surface-treated calcium carbonate is 5 to 100 parts by weight of the fluoropolymer.
The reason why the amount is set to 100 parts by weight is that if the amount is 5 parts by weight or less, there is no effect of improving cut-through resistance, and if it is 100 parts by weight or more, the heat resistance sharply decreases. In addition, a more preferable range is 30 to 80 parts by weight.

In the present invention, if necessary, other components such as a crosslinking monomer, a crosslinking agent, a crosslinking aid, a pigment, a lubricant, a processing aid, a stabilizer, an antioxidant and the like may be added in addition to these components. Good.

[0020]

Next, examples of the fluorine-containing elastomer-coated electric wires and cables of the present invention will be described together with comparative examples.

Example 1 90 parts by weight of a tetrafluoroethylene-propylene copolymer having a number average molecular weight of 100,000,
10 parts by weight of ethylene-tetrafluoroethylene-1,1-dihydroperfluoropropene-1 having a softening point of 225 ° C. and a melt index of 30, 10 parts by weight of triallyl isocyanurate as a crosslinking aid, and stearic acid as a lubricant 1 part by weight of barium and 60 parts by weight of silica surface-treated calcium carbonate “A” (particle size: 1.0 μm) as a filler were weighed and collected.

These were uniformly kneaded with a kneading roll at 50 to 60 ° C. to obtain a fluoropolymer composition of Example 1.

The obtained fluoropolymer composition of Example 1 was heated at a cylinder head temperature of 250 ° C., a cylinder 1 temperature of 280 ° C., and a cylinder 2 temperature of 300.
C., L / D = 22.

An insulated wire core was prepared by twisting two cross-linked polyethylene insulated wires each having a conductor cross-sectional area of 75 mm ² and coated with cross-linked polyethylene. The polymer composition was extruded and coated to a coating thickness of 1.0 mm to obtain an uncrosslinked fluoroelastomer-coated electric wire / cable of Example 1.

The uncrosslinked fluorine-containing elastomer-coated electric wire / cable of Example 1 was passed through an ionizing radiation irradiation furnace for 10 minutes.
Irradiation with a Mrad electron beam was carried out to crosslink, thereby obtaining a fluorine-containing elastomer-coated electric wire / cable.

FIG. 1 shows a cross section of a fluorine-containing elastomer-coated electric wire / cable according to the first embodiment.

In FIG. 1, 1 is a copper stranded wire, 2 is a crosslinked polyethylene insulating layer, 3 is a crosslinked polyethylene insulated wire core,
4 is an inclusion layer and 5 is a fluorine-containing elastomer coating layer.

Although the crosslinked polyethylene is used as the insulating layer here, it is a matter of course that other insulating layers such as a fluorine-containing elastomer, a vinyl chloride resin admixture, various rubbers and the like may be used.

Example 2 90 parts by weight of a tetrafluoroethylene-propylene copolymer having a number average molecular weight of 100,000
10 parts by weight of ethylene-tetrafluoroethylene-1,1-dihydroperfluoropropene-1 having a softening point of 225 ° C. and a melt index of 30, 10 parts by weight of triallyl isocyanurate as a crosslinking aid, and stearic acid as a lubricant 1 part by weight of barium and 80 parts by weight of silica surface-treated calcium carbonate "B" (particle diameter 2.7 μm) as a filler were weighed and collected.

Thereafter, an uncrosslinked fluorine-containing elastomer-coated electric wire / cable of Example 2 was obtained in the same manner as in Example 1.

(Example 3) 70 parts by weight of a tetrafluoroethylene-propylene copolymer having a number average molecular weight of 100,000,
30 parts by weight of ethylene-tetrafluoroethylene-1,1-dihydroperfluoropropene-1 having a softening point of 225 ° C. and a melt index of 30; 1 part by weight of triallyl isocyanurate as a crosslinking aid; stearic acid as a lubricant 1 part by weight of barium and 40 parts by weight of silica surface-treated calcium carbonate "B" (particle diameter 2.7 μm) as a filler were weighed and collected.

Thereafter, an uncrosslinked fluorine-containing elastomer-coated electric wire / cable of Example 3 was obtained in the same manner as in Example 1.

Example 4 85 parts by weight of a tetrafluoroethylene-propylene copolymer having a number average molecular weight of 100,000,
15 parts by weight of ethylene-tetrafluoroethylene-1,1-dihydroperfluoropropene-1 having a softening point of 225 ° C. and a melt index of 30; 1 part by weight of triallyl isocyanurate as a crosslinking aid; stearic acid as a lubricant 1 part by weight of barium and 50 parts by weight of silica surface-treated calcium carbonate "B" (particle diameter 2.7 μm) as a filler were weighed and collected.

Thereafter, an uncrosslinked fluorine-containing elastomer-coated electric wire / cable of Example 4 was obtained in the same manner as in Example 1.

Example 5 80 parts by weight of a tetrafluoroethylene-propylene copolymer having a number average molecular weight of 100,000,
20 parts by weight of ethylene-tetrafluoroethylene-1,1-dihydroperfluoropropene-1 having a softening point of 225 ° C. and a melt index of 30, 1 part by weight of triallyl isocyanurate as a crosslinking aid, and stearic acid as a lubricant 1 part by weight of barium and 50 parts by weight of silica surface-treated calcium carbonate "B" (particle diameter 2.7 μm) as a filler were weighed and collected.

Thereafter, an uncrosslinked fluorine-containing elastomer-coated electric wire / cable of Example 5 was obtained in the same manner as in Example 1.

Comparative Example 1 First, a tetrafluoroethylene-propylene copolymer 100 having a number average molecular weight of 100,000 was used.
Parts by weight, 1 part by weight of triallyl isocyanurate as a cross-linking aid, 1 part by weight of barium stearate as a lubricant, and silica surface-treated calcium carbonate “D” (particle size 0.4 μm) as a filler.
80 parts by weight of m) were weighed and collected.

Thereafter, in the same manner as in Example 1, an uncrosslinked fluorine-containing elastomer-coated electric wire / cable of Comparative Example 1 was obtained.

Comparative Example 2 First, 80 parts by weight of a tetrafluoroethylene-propylene copolymer having a number average molecular weight of 100,000, a softening point of 225 ° C. and a melt index of 3
0 to 20 parts by weight of ethylene to tetrafluoroethylene-1,1-dihydroperfluoropropene-1, 1 part by weight of triallyl isocyanurate as a crosslinking aid, 1 part by weight of barium stearate as a lubricant, silica as a filler 120 parts by weight of the surface-treated calcium carbonate “C” (particle size: 5.0 μm) was weighed and collected.

Thereafter, in the same manner as in Example 1, an uncrosslinked fluorine-containing elastomer-coated electric wire / cable of Comparative Example 2 was obtained.

Comparative Example 3 First, 80 parts by weight of a tetrafluoroethylene-propylene copolymer having a number average molecular weight of 100,000, a softening point of 225 ° C. and a melt index of 3
0 to 20 parts by weight of ethylene to tetrafluoroethylene-1,1-dihydroperfluoropropene-1, 1 part by weight of triallyl isocyanurate as a crosslinking aid, 1 part by weight of barium stearate as a lubricant, silica as a filler 10 parts by weight of the surface-treated calcium carbonate “B” (particle size: 2.7 μm) was weighed and collected.

Thereafter, in the same manner as in Example 1, an uncrosslinked fluorine-containing elastomer-coated electric wire / cable of Comparative Example 3 was obtained.

Comparative Example 4 First, 70 parts by weight of a tetrafluoroethylene-propylene copolymer having a number average molecular weight of 100,000, a softening point of 225 ° C. and a melt index of 3
0 to 30 parts by weight of ethylene to tetrafluoroethylene-1,1-dihydroperfluoropropene-1, 1 part by weight of triallyl isocyanurate as a crosslinking aid, 1 part by weight of barium stearate as a lubricant, silica as a filler 40 parts by weight of the surface-treated calcium carbonate “E” (particle size: 10.3 μm) was weighed and collected.

Thereafter, in the same manner as in Example 1, an uncrosslinked fluorine-containing elastomer-coated electric wire / cable of Comparative Example 4 was obtained.

Comparative Example 5 First, 70 parts by weight of a tetrafluoroethylene-propylene copolymer having a number average molecular weight of 100,000, a softening point of 225 ° C. and a melt index of 3
0 to 30 parts by weight of ethylene to tetrafluoroethylene-1,1-dihydroperfluoropropene-1, 1 part by weight of a cross-linking aid triallyl isocyanurate, 1 part by weight of barium stearate as a lubricant, and steer as a filler Calcium phosphate surface treated calcium carbonate “F” (particle size 1.0μ)
m) was weighed and sampled at 60 parts by weight.

Thereafter, an uncrosslinked fluorine-containing elastomer-coated electric wire / cable of Comparative Example 5 was obtained in the same manner as in Example 1.

(List of fluoropolymer compositions) Table 1 is a list of the fluoropolymer compositions of Examples 1 to 5 and Comparative Examples 1 to 5.

[0048]

[Table 1]

(Method of Testing Characteristics of Fluorine-Containing Elastomer-Coated Wires / Cables) Characteristics tests were performed on the fluorine-containing elastomer-coated wires / cables of Examples 1 to 5 and Comparative Examples 1 to 5.

A. Tensile strength test (measurement of initial tensile strength and initial elongation) Insulated wire cores and the like were respectively extracted from the fluorine-containing elastomer-coated wires and cables of Examples 1 to 5 and Comparative Examples 1 to 5, and the fluorine-containing elastomer coating layer was taken out. JIS-K-630 for each fluorine-containing elastomer coating layer
A tensile test was performed according to No. 1 to measure tensile strength (MPa) and elongation (%).

For each of the fluorine-containing elastomer coating layers, wear samples were prepared by abrasion to a thickness of 0.8 mm, and the samples were also subjected to JIS-K-6301.
A tensile test was performed in accordance with the above, and tensile strength (MPa) and elongation (%) were measured.

B. Dielectric breakdown voltage test A 50 cm long sample of each of the fluorine-containing elastomer-coated electric wires and cables of Examples 1 to 5 and Comparative Examples 1 to 5 was collected.

Each of these was immersed in water, and then an alternating voltage was applied between the conductor of the fluorine-containing elastomer-coated electric wire / cable and water at a rate of 1,000 V / min while the breakdown voltage was measured. .

C. Heat Aging Resistance (Measurement of Tensile Strength and Elongation after Thermal Aging) For the fluorine-containing elastomer-coated electric wires and cables of Examples 1 to 5 and Comparative Examples 1 to 5, samples having a length of 50 cm were collected.

These fluorinated elastomer-coated electric wires and cables were put into a gear aging heat aging test tank having a temperature of 232 ° C. and an air displacement of 200 times / Hr, and heat-aged for 7 days.

After the heat aging, each of the insulated wire cores and the like was extracted to take out the fluorine-containing elastomer coating layer, and each of the fluorine-containing elastomer coating layers was subjected to JIS-K-
A tensile test was performed according to 6301, and the tensile strength (MP
a) and elongation (%) were measured.

D. Cut-through resistance Regarding the fluorine-containing elastomer-coated electric wires and cables of Examples 1 to 7 and Comparative Examples 1 to 5, UL subject 75
A cut-through resistance test was performed at 200 ° C. in accordance with No. 8.

[Characteristic Test Results of Fluorine-Containing Elastomer-Coated Wires and Cables] Table 2 shows the characteristic test results of the fluorinated elastomer-coated wires and cables of Examples 1 to 5 and Comparative Examples 1 to 5.

[0059]

[Table 2]

As can be seen from Table 2, the insulation of the fluorine-containing elastomer-coated electric wire / cable of Comparative Example 1 has an extremely low dielectric breakdown voltage of 12 kv.

The fluorine-containing elastomer-coated electric wire of Comparative Example 2
The cable has the disadvantage that the initial tensile strength is low and the elongation after heat aging is reduced to 55% of the initial value.

The fluorine-containing elastomer-coated electric wire of Comparative Example 3
The cable has the poorest cut-through resistance of 50.

The fluorine-containing elastomer-coated electric wire of Comparative Example 4
The cable has the lowest initial tensile strength and the lowest breakdown voltage of 10 kv.

The fluorine-containing elastomer-coated electric wire of Comparative Example 5
The cable has a low initial tensile strength and a dielectric breakdown voltage of 1
It is as low as 2kv.

On the other hand, the fluorine-containing elastomer-coated electric wires and cables of Examples 1 to 5 have a large initial tensile strength and elongation, a large tensile strength and elongation after thermal aging, and a large dielectric breakdown voltage. Furthermore, the cut-through resistance is excellent.

[0066]

The fluorine-containing elastomer-coated electric wire of the present invention
Cables have excellent flexibility, heat resistance, heat stability, electrical insulation, oil resistance, chemical resistance, and flame retardancy.
It has high initial tensile strength and elongation, which have been regarded as difficult points, and high tensile strength and elongation after thermal aging. In addition, it has high dielectric breakdown voltage and excellent cut-through resistance. is there.

[Brief description of the drawings]

FIG. 1 shows a cross section of a fluorine-containing elastomer-coated electric wire / cable according to a first embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Copper stranded wire 2 Insulation layer 3 Insulated wire core 4 Inclusion layer 5 Fluorine-containing elastomer coating layer

Claims (3)

[Claims] 1. A fluoroelastomer-coated electric wire or cable comprising a conductor or an outer periphery of an insulated wire core coated with a fluoropolymer composition, wherein the fluoropolymer composition is silica based on 100 parts by weight of the fluoropolymer. A fluorine-containing elastomer-coated electric wire or cable comprising 5 to 100 parts by weight of surface-treated calcium carbonate. 2. The method according to claim 1, wherein the fluoropolymer is a tetrafluoroethylene-propylene copolymer, an ethylene-tetrafluoroethylene copolymer, or a tetrafluoroethylene copolymer.
The fluoroelastomer-coated electric wire / cable according to claim 1, characterized in that it is a blended fluoropolymer of a propylene copolymer and an ethylene-tetrafluoroethylene copolymer. 3. The fluorine-containing elastomer-coated electric wire or cable according to claim 1, wherein the calcium carbonate has a particle size of 10 μm or less.