JPH07335027A - Fluorine containing elastomer covered electric wire/ cable and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a novel fluorine containing elastomer covered electric wire/cable excellent in bending fatigue resistance, and a method for manufacturing the same. CONSTITUTION:In a fluorine containing elastomer covered electric wire/cable having covering layers 2, 4 formed on a conductor 1 or around an electric wire core 3, the covering layers 2, 4 is a composition including 0.5-5 pts.wt. of each of an organic peroxide, metal oxide and a crosslinking agent mixed with 100 pts.wt. of a tetrafluoroethylene-propylene copolymer, where a crosslinking degree exceeds 90% in (simple) gel percentage and 100% modulus is set to 3MPa or less.

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 having a coating layer mainly composed of a tetrafluoroethylene-propylene copolymer and a method for producing the same.

[0002]

2. Description of the Related Art Generally, as coating materials for electric wires and cables, there are tetrafluoroethylene-propylene copolymers in addition to chloropropylene rubber, chlorosulfonated polyethylene rubber and the like. This tetrafluoroethylene-propylene-based copolymer is a crosslinkable fluorine-containing elastomer copolymer having a high degree of thermal stability, electrical insulation, heat resistance, oil resistance, chemical resistance, and flame retardancy. By coating the polymer on the conductor or on the outer periphery of the electric wire core and crosslinking it by high pressure steam or lead canning crosslinking using peroxide, it is possible to obtain an electric wire / cable having extremely excellent characteristics.

[0003]

By the way, the electric wire / cable using the coating material made of the tetrafluoroethylene-propylene copolymer is widely used such as chloropropylene rubber and chlorosulfonated polyethylene rubber. Since the bending fatigue resistance is extremely inferior to that of electric wires and cables made of coating materials, the coating layer will crack in a relatively short time when used in an environment where repeated bending is applied. There was a point.

Therefore, the present invention has been devised to effectively solve the above problems, and its purpose is to provide a novel fluorine-containing elastomer-coated electric wire / cable excellent in bending fatigue resistance and a method for manufacturing the same. Is provided.

[0005]

In order to solve the above-mentioned problems, the present invention provides a fluorine-containing elastomer-coated electric wire / cable in which a coating layer is formed on a conductor or on the outer periphery of an electric wire core,
The coating layer is composed of a composition in which an organic peroxide, a metal oxide, and a crosslinking aid are mixed in a range of 0.5 to 5 parts by weight with respect to 100 parts by weight of a tetrafluoroethylene-propylene copolymer. , Cross-linking degree is 90% or more in gel (simple gel) fraction, and 100% modulus is 3M
Pa or less.

The tetrafluoroethylene-propylene copolymer which is the main component of this composition includes, in addition to the main components tetrafluoroethylene and propylene, components copolymerizable with them, such as ethylene, butene-1, and isobutene. , Acrylic acid and its alkyl ester, methacrylic acid and its alkyl ester, vinyl fluoride, vinylidene fluoride, hexafluoropropene, chloroethyl vinyl ether, glycidyl vinyl ether, chlorotrifluoroethylene, perfluoroalkyl vinyl ether, etc. Good. The tetrafluoroethylene-propylene-based copolymer is preferably selected from the range of the tetrafluoroethylene / propylene content molar ratio of 95/5 to 30/70 from the viewpoint of heat resistance, moldability, etc., and particularly preferably. , 90/10 to 45/5
The range is 5. Further, the content of components other than the main component that is appropriately added is preferably selected from the range of 50 mol% or less, particularly 30 mol% or less. The number average molecular weight of the tetrafluoroethylene-propylene copolymer is preferably selected from the range of 20,000 to 150,000, preferably 30,000 to 100,000 from the viewpoint of extrudability and mechanical strength, and the number average molecular weight is too large. And cracks easily occur in the molded body, on the other hand, if it is too small mechanical strength becomes insufficient, the number molecular weight adjustment in this case, monomer concentration, polymerization initiator concentration, monomer-to-polymerization initiator amount A method of directly adjusting the molecular weight of the polymer produced by the operation of the copolymerization reaction conditions such as the ratio, the polymerization temperature and the use of a chain transfer agent, or a high molecular weight copolymer is produced during the copolymerization reaction and heated in the presence of oxygen. It can be carried out by a method of lowering the molecular weight by treatment.

As the organic peroxide mixed with the tetrafluoroethylene-propylene copolymer, diacyl peroxide such as dibenzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, t -Monoperoxy compounds such as peroxyesters such as butylperoxyacetate, t-butylperoxyisopropyl carbonate, t-butylperoxybenzoate and 2,5-dimethyl-
2,5-di- (t-butylperoxy) -hexyne-
3,2,5-Dimethyl-2,5-di- (t-butylperoxy) -hexane, 1,4-bis- (t-butylperoxyisopropyl) benzene, 1.3-bis- (t-
Examples thereof include peroxy compounds such as butylperoxyisopropyl) benzene and 2,5-dimethyl-2,5-di- (benzoylperoxy) -hexane. And, the reason for limiting the blending amount thereof to 0.5 to 5 parts by weight is that
If it is less than 5 parts by weight, the cross-linking will be insufficient and good mechanical properties will not be obtained, and if it exceeds 5 parts by weight, there will be no further effect and rather heat resistance and flex fatigue resistance will be reduced. This is because a large amount of methane gas is suppressed during LCM crosslinking, causing expansion of the coating layer.

Similarly, the amount of the metal oxide compounded is limited to 0.5 to 5 parts by weight, because the amount of less than 0.5 parts by weight causes insufficient crosslinking, so that the expansion of the coating layer at the time of LCM crosslinking. This is because there is no inhibitory effect, and even if it exceeds 5 parts by weight, there is no further effect, and conversely the flexural fatigue resistance is greatly reduced, or the viscosity becomes high and extrusion becomes difficult.

Further, examples of the crosslinking aid include allyl compounds, sulfur, organic amines, maleimides, methacrylates, divinyl compounds and the like. Preferably polyallyl compounds such as diallyl phthalate, triallyl phosphate, triallyl dianurate, triallyl isocyanurate, diallyl melamine, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate,
Oxime compounds such as polyhydric alcohol methacrylate and para-benzoquinone dioxime and P, P'-dibenzoquinone dioxime are used, and polyallyl compounds are particularly desirable. Then, the amount of the cross-linking auxiliary compounded is similarly 0.5 to
The reason why the amount is limited to 5 parts by weight is that if it is less than this range, the crosslinking becomes insufficient, and if it is more than this range, bleeding occurs and the bite of the material into the screw becomes poor. In the present invention, the amount of the metal oxide and the crosslinking aid compounded is limited to 0.5 to 5 parts by weight, but a remarkable effect can be obtained in the range of 1 to 4 parts by weight.

The LMC crosslinking method is a Liquid-Curning-Media developed by Dupont.
This is an abbreviation for m (liquid cross-linking medium), and this mechanism is a method of continuously passing a cable through a mixed molten salt of potassium nitrate, sodium nitrate and sodium nitrite to cross-link, which saves workers, It has merits such as simplification and no contact with oxygen due to cross-linking in liquid. However, since the pressure is only about 1 to 3 atm, it is expected that foaming will occur if the material contains water, so it is preferable to use an extruder having an extruder vacuum degassing facility.

In the present invention, in addition to the above components, a pigment, a filler, a lubricant, an extrusion aid, and
You may mix a stabilizer etc.

[0012]

In the present invention, the composition as described above is cross-linked using the LMC cross-linking method, so that the degree of cross-linking (gel fraction) is 90% or more and the 100% modulus is 3M.
An electric wire / cable having a coating layer having an extremely unique property of Pa or less can be obtained. That is, the inventors have found that such a coating layer having extremely unique properties can be obtained only by crosslinking the composition comprising the above components by the LCM crosslinking method, and have reached the present invention. Therefore, according to the present invention, since the degree of crosslinking is 90% or more, sufficient strength can be obtained, and the 100% modulus is 3 MPa or less, so that it is highly flexible and has excellent flex fatigue resistance. Can be improved.

[0013]

EXAMPLES Examples of the present invention will be described in detail below.

(Example) As shown in Examples of Table 1, tetrafluoroethylene-propylene copolymer was mixed with an organic peroxide, a cross-linking aid and a metal oxide.
After uniformly kneading with a roll heated to 0 to 60 ° C. for 15 minutes to form a composition, these compositions were subjected to head: 80 ° C., cylinder 1: 80 ° C., cylinder 2:60 as shown in FIG. 40m / m extruder set at ℃ (L / D = 2
2) is used to extrude and coat the outer circumference of a copper stranded wire 1 having a cross-sectional area of 0.75 mm ² to a thickness of 1.1 mm to form a coating layer 2, and then dip it in a molten salt at 195 ° C. for 5 minutes. By doing this, the coating layer 2 is crosslinked to form seven types (Examples 1 to 1).
The insulated wire 3 of 5) was manufactured.

Next, 5 out of these 7 types of insulated wires
As shown in FIG. 1, three kinds of insulated wires of the same kind were used, and the same composition as above was applied to the outer circumference by using a twin-screw vent extruder to obtain a thickness of 1.8 mm. Extrusion coating is applied to form the sheath 4, and the sheath 4 is cross-linked by being immersed in a molten salt at 195 ° C. for 5 minutes to form a sheath having a diameter of 11.0 mm.
A variety of sample cables (Examples 1-5) were manufactured.

Then, the gel fraction, tensile properties and flex fatigue resistance of each of these sample cables and sample electric wires were evaluated, and the results are shown in the lower column of Table 1. The simple gel fraction was determined as follows after a sample cut from the cable by a predetermined amount was immersed in tetrahydrofuran at 70 ° C. for 24 hours. Simple gel (%) = weight after dissolution / initial weight × 10
0. In the case of the tensile property evaluation method, the coating layer 2 (tube) was worn for the sample electric wire and the sheath 4 for the sample cable, and a 1 mm sample was prepared.
It was carried out according to 01. The flex fatigue resistance is JISC-
According to the method according to 3004, the cable was pressed against a mandrel having a diameter of 10 times in an atmosphere of a constant temperature of 50 ° C. to repeatedly bend the cable, and the number of times of bending until the sheath cracked was evaluated.

(Comparative Examples 1 and 2) As a crosslinking method, lead can crosslinking (145 ° C.) and high pressure steam crosslinking (210 ° C. × 3 minutes)
Sample cables were produced by using the same composition and manufacturing method as those of the examples except that the above-mentioned was used, and these sample cables were evaluated in the same manner as the examples.

(Comparative Examples 3 to 5) Other than using a composition prepared by mixing only two kinds of an organic peroxide, a crosslinking aid and a metal oxide with a tetrafluoroethylene-propylene copolymer. Sample cables were prepared using the same crosslinking method and manufacturing method as in the examples, and the same evaluations as those in the examples were performed on these sample cables.

[0019]

[Table 1]

As a result, as is clear from Table 1, the sample cables of Examples 1 to 5 according to the present invention and Example 1,
Each of the sample electric wires of No. 2 had a gel fraction of 90% or more, good tensile properties, and showed excellent bending fatigue resistance of 200,000 cycles or more until repeated cracking. No expansion of the outer layer of the cable, biting into the screw, or failure occurred.

On the other hand, Comparative Examples 1 and 2 which were cross-linked by using the lead can cross-linking or the high pressure steam cross-linking method,
The tensile properties were good, but the bending fatigue resistance was significantly inferior to the examples. In addition, in Comparative Example 3 in which no organic peroxide was added, the gel fraction could not be measured, the tensile properties were significantly reduced, and the expansion of the cable outer layer was large, so that the packing portion at the outlet of the cross-linking pipe was treated. It was broken and damaged, and it was impossible to measure flex fatigue resistance. Furthermore, Comparative Example 4 in which the metal oxide and the crosslinking aid were not added
Similarly to Comparative Example 3, the bending fatigue resistance of Nos. 5 and 5 could not be evaluated.

[0022]

In summary, according to the present invention, by using a predetermined composition and the LMC cross-linking method, electric wire characteristics,
In particular, it has excellent effects such as flexural fatigue resistance being greatly improved and highly reliable fluorine-containing elastomer-coated electric wires and cables can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

[Explanation of symbols]

 1 conductor 2 coating layer 3 insulated wire 4 sheath

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Claims (2)

[Claims] 1. A fluorine-containing elastomer-coated electric wire / cable in which a coating layer is formed on a conductor or on the outer periphery of an electric wire core, wherein the coating layer is an organic peroxide with respect to 100 parts by weight of a tetrafluoroethylene-propylene-based copolymer. Of the composition, a metal oxide, and a cross-linking auxiliary agent in the range of 0.5 to 5 parts by weight, and the degree of cross-linking is gel (simple gel).
A fluorine-containing elastomer-coated electric wire / cable having a fraction of 90% or more and a 100% modulus of 3 MPa or less. 2. A conductor comprising a composition in which an organic peroxide, a metal oxide and a crosslinking aid are mixed in an amount of 0.5 to 5 parts by weight with respect to 100 parts by weight of a tetrafluoroethylene-propylene copolymer. After coating the upper part or the outer periphery of the wire core to form a coating layer, the coating layer is coated with LCM (Liquid-
Curing-Medium) Cross-linking method, and a method for producing a fluorine-containing elastomer-coated electric wire / cable.