JPH07126468A - Fluororesin composition and insulated electric wire and heat-shrinkable tube made therefrom respectively - Google Patents

Abstract

PURPOSE:To provide a fluororesin composition excellent in mechanical properties and abrasion resistance in the initial stage and after heat aging, exhibiting an excellent flexibility since a fluoroelastomer component is contained and useful for an insulated electric wire which is used for wiring in an automobile or a heat-shrinkable tube. CONSTITUTION:This fluororesin composition is prepared by applying ionization radiation to a mixture containing (A) a vinylidene fluoride-hexafluoropropylene- tetrafluoroetylene-ethylene or propylene-based fluoroelastomer and (B) a fluorovinylidene-based fluoropolymer or/and an ethylene-tetrafluoroethylene-based fluoropolymer in a weight ratio of 95/5 to 40/60 so as to cross-link it. From this resin composition, an insulated electric wire and a heat-shrinkable tube can be produced.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention provides a fluororesin composition suitable for use in applications requiring high heat resistance and wear resistance such as an automobile engine room, an insulated wire and a heat-shrinkable tube made therefrom. It is provided.

[0002]

2. Description of the Related Art Fluoroelastomers containing vinylidene fluoride and propylene hexafluoride as repeating units are used for insulated electric wires and heat-shrinkable tubes that require high heat resistance and oil resistance in automobile engine rooms, etc. A resin composition mainly composed of a fluoroelastomer having repeating units of vinylidene chloride, propylene hexafluoride and ethylene tetrafluoride is used. Insulated wires and heat-shrinkable tubes using these fluoroelastomers are excellent in that they do not lose their initial mechanical properties even when exposed to severe thermal conditions such as exposure to temperatures as high as 250 ° C for 1 week. In addition to showing excellent heat resistance, it also has excellent oil resistance to various oils such as engine oil and brake oil, and the amount of its use has expanded more and more in recent years.

Further, in automobile applications, not only the characteristics such as heat resistance and oil resistance but also abrasion resistance are important required characteristics. However, insulated wires and heat shrinkable tubes using the above-mentioned fluororesin composition are When exposed to a high temperature condition for a long time, there was a problem that the wear resistance was remarkably reduced as compared with the initial value. Further, in the above applications, a tetrafluoroethylene-based polymer (PTFE resin), a tetrafluoroethylene-perfluoroalkylvinylether-based copolymer (PFA resin), or a hexafluoropropylene-tetrafluoroethylene-based copolymer (F
Insulated wires and heat-shrinkable tubes using fluoropolymers such as EP resin) are also used.

[0004]

[Problems to be Solved by the Invention] PTFE resin and PFA
Insulated wires and heat-shrinkable tubes using fluoropolymers such as resin and FEP resin are excellent in heat resistance and oil resistance, and also have abrasion resistance. Insulated wires and heat-shrinkable tubes using the fluoroelastomer-based resin composition. Is superior to that of No. 1, and has the advantage that the wear resistance does not decrease even when exposed to high temperature conditions for a long time.

On the other hand, however, the insulated wires and heat-shrinkable tubes using the above fluoropolymer are harder than those using the resin composition containing fluoroelastomer as a main component. There were problems such as poor workability.

[0006]

Means for Solving the Problems As a result of diligent study on such problems, the present inventor has (A) a fluoroelastomer containing vinylidene fluoride, hexafluoropropylene, tetrafluoroethylene, ethylene or propylene as a main repeating unit. And (B) a fluoropolymer having vinylidene fluoride as a main repeating unit or a mixture of ethylene and a fluoropolymer having ethylene tetrafluoride as a main repeating unit as a main component, wherein the fluoroelastomer (A ) And the fluoropolymer (B) in a mixing ratio of 95/5 to 40 to 60 by weight, a fluororesin composition in which a resin composition is crosslinked by irradiation with ionizing radiation, and insulation from the resin composition The heat-shrinkable tube made from the electric wire and the resin composition has excellent heat resistance and has abrasion resistance even when exposed to high temperature conditions for a long time. Less down, we found to be excellent in flexibility, and have completed the present invention based on this finding.

The present invention will be described in detail below. The fluoropolymer (B) containing vinylidene fluoride as a main repeating unit of the present invention means a homopolymerization polymer of vinylidene fluoride, a copolymer of vinylidene fluoride and propylene hexafluoride, a copolymer of vinylidene fluoride and ethylene tetrafluoride. , Vinylidene fluoride, propylene hexafluoride, and tetrafluoroethylene copolymer can be exemplified, and the melting point of these vinylidene fluoride polymers is about 60 to 170.
It is in the range of ° C.

Similarly, a fluoropolymer (B) containing ethylene and tetrafluoroethylene as a main repeating unit is
Included are copolymers of ethylene and tetrafluoroethylene, fluoropolymer-based copolymers of ethylene, tetrafluoroethylene and hexafluoropropylene, etc., and the melting point of these ethylene-tetrafluoroethylene-based polymers is approximately Two
It is in the range of 20 to 275 ° C.

Further, vinylidene fluoride, propylene hexafluoride, tetrafluoroethylene, and fluoroelastomer (A) containing ethylene or propylene as a main repeating unit,
A fluoroelastomer having a combination of the above monomers as a basic monomer group, further comprising chlorotrifluoroethylene, pentafluoropropylene, butene-1, isobutene, ethyl vinyl ether, fluoro vinyl ether, perfluoroalkyl vinyl ether, fluoroalkyl group-containing acrylate or methacrylate. A fluoroelastomer obtained by copolymerizing a small amount of a monomer such as phosphonitrile (50 mol% or less, preferably 30 mol% or less) with the above basic monomer group can also be used.

The fluoroelastomer (A) referred to herein means a fluorine-containing polymer having no crystal component, and the vulcanized product thereof has a property of elastic recovery in a wide temperature range,
It is also commonly called "fluororubber". Similarly, the fluoropolymer (B) refers to a fluorine-containing polymer having a crystalline component, has a property of not having elastic restoring property, and is commonly called a “fluorine resin”.

The mixing ratio of the fluoroelastomer (A) and the fluoropolymer (B) is not particularly limited, but the initial abrasion resistance and flexibility, and the shape stability when used as a heat shrinkable tube. From the viewpoint, the mixing ratio of the fluoroelastomer (A) and the fluoropolymer (B) is preferably 95/5 to 40 to 60, and particularly preferably 90/10 to 50/50 by weight. Is obtained. When the amount of the component (B) is less than 5 parts by weight, the initial wear resistance of the electric wire and the heat-shrinkable tube is poor, and particularly when the heat-shrinkable tube is used, the shape stability (natural shrinkage) after expansion and fixing is poor. Further, if the amount of the component (B) exceeds 60 parts by weight, the electric wire and the heat shrinkable tube have poor flexibility.

To the above resin composition, a polyfunctional monomer such as trimethylolpropane trimethacrylate, triallyl cyanurate, triallyl isocyanurate, and triallyl trimellitate is preliminarily added for the purpose of promoting crosslinking by irradiation with ionizing radiation. You may mix. The compounding amount of the polyfunctional monomer is not particularly limited, but is, for example, 0.5 to
10 parts by weight is preferred.

Further, metal oxides such as zinc oxide, calcium oxide, magnesium oxide and lead oxide; metal hydroxides such as calcium hydroxide, magnesium hydroxide and aluminum hydroxide; calcium carbonate, lead carbonate, aluminum carbonate and the like. Metal carbonates; reinforcing inorganic fillers and stabilizers such as silica, talc, and clay; various additives such as lubricants, antioxidants, carbon black, colorants, plasticizers, and foaming agents can be blended as necessary. .

The fluororesin composition of the present invention comprises the above (A)
If necessary, various additives may be added to the base resin or elastomer containing the component and the component (B) by means such as kneading and various molding may be performed as it is, or after processing into a molding powder such as pellets, , Molded into various molded products.

In particular, the above-mentioned fluororesin composition can be compounded by using a known mixing device such as a pressure kneader, a Banbury mixer, an open roll mixer, a single-screw or twin-screw mixer, and molding. Molding into a product can be carried out by a known molding means such as extrusion coating, extrusion molding, injection molding or press molding. Particularly, for insulated wires, heat shrinkable tubes, etc., if a melt extruder or the like is used. good.

Further, the above-mentioned fluororesin composition is crosslinked by an ionizing radiation source, so that an insulated wire and a heat-shrinkable tube which are excellent in mechanical properties and abrasion resistance in the initial stage and after heat aging intended by the present invention. Is necessary from the viewpoint of obtaining. Examples of the ionizing radiation source include accelerated electron beams, gamma rays, X-rays, ultraviolet rays, and alpha rays, but from the viewpoint of industrial use such as the ease of using the radiation source, the reaching distance of ionizing radiation, and the crosslinking processing speed, accelerated electron beams are used. Can be preferably used. The electron beam acceleration voltage may be set to 500 kV to 2 MV, and the irradiation dose may be set to 30 to 300 kGy.

In addition to the irradiation with ionizing radiation, thermal crosslinking after the blending of an organic peroxide such as dicumyl peroxide or 3-bis (t-butylperoxyisopropyl) peroxide is also possible for the above crosslinking. is there. In order to obtain a heat-shrinkable tube from the resin composition of the present invention, the resin composition is molded into a tube shape by, for example, an extrusion molding method, and then crosslinked by ionizing radiation, and then compressed into a tube under heating conditions, for example. A heat-shrinkable tube can be obtained by a method in which the tube is expanded in diameter by a method of feeding air and then cooled and fixed. The heat-shrinkable tube produced in this manner is restored to a previously stored tube-shaped object by heating it to a temperature above its melting point.

Further, the outer circumference of a multi-core twisted insulated wire of a single core or a plurality of insulated wires made of a conductor such as copper is coated with the fluororesin composition of the present invention by a molding means such as extrusion coating, and further ionized. An insulated cable (electric wire) can be obtained by irradiating radiation and crosslinking.

[0019]

The present invention will be described in more detail. For example, a nickel-plated annealed copper conductor with a wire diameter of 0.127 mmφ 19
On the twisted conductor, vinylidene fluoride-propylene hexafluoride-tetrafluoroethylene-ethylene quaternary fluoroelastomer [ML _{1 + 4} (100 ° C.) 76] and vinylidene fluoride-propylene hexafluoride copolymer Polymer (melting point 141
C.) with a resin composition of 4 parts by weight of zinc white and 3 parts by weight of triallyl isocyanurate to 100 parts by weight of a 6: 4 mixture (weight ratio). .

When the obtained insulated wire was irradiated with an electron beam having an accelerating voltage of 1 MV for 100 kGy, the tensile strength, elongation, and abrasion resistance of the sample insulated wire (values measured by the abrasion resistance tester shown in FIG. 1) As a result of examining each of n = 3,
The initial tensile strength is 2.6 kg / mm ² , elongation 280%, wear resistance 564 cycles, while the sample after heat aging has a tensile strength 2.4 kg / mm ² , elongation 296%, wear resistance 453. It was a cycle, and no significant change was observed in the wear resistance as well as the mechanical properties of the insulator before and after heat aging.

On the other hand, in the above resin composition, a ternary fluoroelastomer of vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene [ML _{1 + 4} (100 ° C.) 55] is used as the fluoroelastomer. , The insulated wire which was extrusion-coated with the same thickness and irradiated with the same dose of electron beam had an initial tensile strength of the insulator of 2.6 kg / mm ² ,
The elongation was 272% and the wear resistance was 606 cycles, while the sample after heat aging had a tensile strength of 2.2 kg / mm ² , an elongation of 268% and wear resistance of 57 cycles. Although no significant change was observed in tensile properties, there was a problem that wear resistance was significantly reduced.

That is, in the present invention, a specific fluoropolymer (B) is replaced by a specific fluoropolymer instead of the conventional ternary fluoroelastomer of vinylidene fluoride-propylene hexafluoride-tetrafluoroethylene as the fluoroelastomer. Only when the vinylidene-hexafluoropropylene-tetrafluoroethylene-ethylene fluoroelastomer (A) is blended, the mechanical properties of the insulator as well as abrasion resistance are maintained before and after heat aging, and the heat aging is also performed. The abrasion resistance is less deteriorated by the above, and since it contains the fluoroelastomer component, it is also excellent in flexibility, which is a particularly excellent effect.

Hereinafter, the present invention will be described in more detail with reference to Examples, but these do not limit the scope of the present invention.

[Examples] Resin compositions having the formulations shown in Tables 1 to 3 below were kneaded for 10 minutes by a pressure kneader set to an initial temperature of 100 to 150 ° C, and then granulated into pellets, or sheet molded products were cut. And made into pellets. This pellet is melt extruder (full flight screw, L / D
= 22, compression ratio = 2.5), wire coating and tube molding were performed.

The wire coating is a conductor having a diameter of 0.127.
A 19-twisted conductor of mmφ nickel-plated annealed copper wire was used, and the coating thickness was set to 0.45 mm. Further, the tube was formed by setting the inner diameter to 4.5 mmφ and the wall thickness to 0.50 mm. After coating the wire and molding the tube, an electron beam having an accelerating voltage of 1 MV was irradiated with 100 kGy to obtain a test sample.

The samples were tested for resistance by measuring the initial tensile strength and elongation of the insulator, and the number of wear cycles (cycles) until the edges electrically contacted the conductor with the wear resistance tester shown in FIG. The wear resistance was evaluated. In the abrasion resistance test of the tube, a sample in which the tube was covered with an aluminum rod having an outer diameter of 4.4 mmφ was evaluated in the same manner as in the case of the electric wire. Further, the tensile strength, elongation, and wear resistance of the insulator were also evaluated for the sample heat-aged for 168 hours in a gear oven at 250 ° C.

(Example 1) Insulated wire using a resin composition mainly composed of a mixture of vinylidene fluoride, propylene hexafluoride, tetrafluoroethylene, and a fluoroelastomer having ethylene as a repeating unit and a vinylidene fluoride resin. Was manufactured according to the above formulation, and the insulated wire samples obtained were subjected to various tests. The results are shown in Table 1. according to it,
The insulator is excellent in mechanical properties at the initial stage and after the heat aging test, and the wear resistance is little changed before and after the heat aging.

Example 2 An insulated wire using a resin composition mainly composed of a mixture of fluoroelastomer containing vinylidene fluoride, propylene hexafluoride, tetrafluoroethylene and ethylene as a repeating unit and ETFE resin is prescribed as above. Various tests were performed on the obtained insulated wire samples manufactured in accordance with. The results are shown in Table 1. According to it, the insulator has excellent mechanical properties after the initial and heat aging tests,
The wear resistance also shows little change before and after heat aging.

[0028]

[Table 1]

(* 1) Technoflon RBX915N (A
Made by USIMON; α-olefin = ethylene (* 2) Kainer 2800 (made by Mitsubishi Petrochemical Co., Ltd.) (* 3) Neoflon EP610 (Daikin Industries, Ltd.)
Made)

Example 3 A tube using a resin composition mainly composed of a mixture of vinylidene fluoride, hexafluoropropylene, tetrafluoroethylene, and a fluoroelastomer having ethylene as a repeating unit and a vinylidene fluoride resin. Various tests were performed on the heat-shrinkable tube samples produced according to the above formulation. The results are shown in Table 2. According to this, the tube is excellent in mechanical properties in the initial stage and after the heat aging test, and the wear resistance is little changed before and after the heat aging.

Further, after preheating this tube in a gear oven at 170 ° C. for 3 minutes, it was expanded radially until the inner diameter became 10 mmφ by a method of sending compressed air into the tube, and immediately taken out from the gear oven. It was cooled with water and fixed in shape to obtain a heat-shrinkable tube. This heat-shrinkable tube is covered with an aluminum rod with an outer diameter of 6.0 mmφ and the temperature is 150 ° C.
When left in the gear oven of No. 5 for 5 minutes, it was confirmed that heat shrinks while fitting around the aluminum rod.

Example 4 A tube using a resin composition mainly composed of a mixture of vinylidene fluoride, propylene hexafluoride, tetrafluoroethylene and a fluoroelastomer having ethylene as a repeating unit and an ETFE resin was prepared according to the above-mentioned formulation. Various tests were conducted on the tube samples produced and obtained. The results are shown in Table 2. According to this, the tube is excellent in mechanical properties in the initial stage and after the heat aging test, and the wear resistance is little changed before and after the heat aging.

Further, after preheating this tube in a gear oven at 230 ° C. for 3 minutes, it was expanded radially until the inner diameter became 10 mmφ by a method of sending compressed air into the tube, and immediately taken out from the gear oven. It was cooled with water and fixed in shape to obtain a heat-shrinkable tube. This heat-shrinkable tube is put on an aluminum rod with an outer diameter of 6.0 mmφ and the temperature is 240 ° C.
When left in the gear oven of No. 5 for 5 minutes, it was confirmed that heat shrinks while fitting around the aluminum rod.

[0034]

[Table 2]

(* 1) Technoflon RBX915N (A
Made by USIMON; α-olefin = ethylene (* 2) Kainer 2800 (made by Mitsubishi Petrochemical Co., Ltd.) (* 3) Neoflon EP610 (Daikin Industries, Ltd.)
Made)

(Comparative Example 1) An insulated wire using a resin composition based on fluoroelastomer alone containing vinylidene fluoride, propylene hexafluoride, ethylene tetrafluoride, and ethylene as repeating units was produced in accordance with the above-mentioned formulation, and was obtained. Various tests were performed on the insulated wire samples. The results are shown in Table 3. According to this, the insulator has excellent mechanical properties after the initial test and after the heat aging test, but the initial wear resistance is poor.

(Comparative Example 2) A tube using a resin composition containing a fluoroelastomer alone containing vinylidene fluoride, propylene hexafluoride and ethylene tetrafluoride as repeating units was manufactured according to the above formulation, and a tube sample was obtained. Was subjected to various tests. The results are shown in Table 3. According to this, the tube is excellent in mechanical properties of the insulator at the initial stage and after heat aging, but is inferior in initial abrasion resistance.

Further, after preheating this tube in a gear oven at 120 ° C. for 3 minutes, it was expanded radially until the inner diameter became 10 mmφ by a method of sending compressed air into the tube, and immediately taken out from the gear oven. It was cooled with water and fixed in shape to obtain a heat-shrinkable tube. However, the inner diameter of this tube gradually shrank at room temperature, and after 24 hours, the inner diameter shrank to 6.7 mmφ, which was insufficient as a heat-shrinkable tube.

(Comparative Example 3) An insulated electric wire was manufactured according to the above-mentioned prescription, using a resin composition containing vinylidene fluoride, propylene hexafluoride, and tetrafluoroethylene as repeating units, and a vinylidene fluoride resin-based resin composition. Then, various tests were performed on the obtained insulated electric wire samples. The results are shown in Table 3. According to this, although the insulator has excellent mechanical properties in the initial stage and after the heat aging, and the initial abrasion resistance is as good as those in Examples 1 to 4, Inferior in wear resistance after heat aging.

(Comparative Example 4) A tube using a fluoroelastomer having vinylidene fluoride, propylene hexafluoride, and tetrafluoroethylene as repeating units and a resin composition containing ETFE resin as a main component was manufactured according to the above-mentioned formulation, and was obtained. The obtained tube sample was subjected to various tests. The results are shown in Table 3. According to this, although the tube has excellent mechanical properties of the insulator in the initial stage and after the heat aging, and the initial wear resistance is as good as those in Examples 1 to 4, Inferior wear resistance after heat aging.

[0041]

[Table 3]

(* 1) Technoflon RBX915N (A
Made by USIMON; α-olefin = ethylene (* 2) Kainer 2800 (made by Mitsubishi Petrochemical Co., Ltd.) (* 3) Neoflon EP610 (Daikin Industries, Ltd.)
(* 4) Viton B50 (DuPont)

[0043]

As described above, when the fluororesin composition of the present invention is used, an insulated wire and a heat shrinkable tube having excellent mechanical properties and abrasion resistance at the initial stage and after heat aging can be obtained. In addition, the problem of deterioration of wear resistance due to heat aging can be solved, and since the fluoroelastomer component is included in the resin composition, it is also excellent in flexibility, and it can be used for insulated wires and heat shrinkage used for wiring in automobiles. The utility value as a tube is very large.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the concept of an abrasion resistance tester used for measuring the abrasion resistance of an insulated wire and a heat shrinkable tube according to the present invention. 1 sample 2 frame 3 conductor or aluminum rod 5 edge 6 short circuit detector

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location // (C08L 27/12 27:16)

Claims (3)

[Claims] 1. A fluoroelastomer containing (A) vinylidene fluoride, propylene hexafluoride, tetrafluoroethylene, and ethylene or propylene as a main repeating unit, and (B).
A fluoropolymer having vinylidene fluoride as a main repeating unit or / and a mixture of ethylene and a fluoropolymer having ethylene tetrafluoride as a main repeating unit as a main component, and the fluoroelastomer (A) The mixing ratio with the fluoropolymer (B) is 95 / by weight.
A fluororesin composition, wherein the resin composition of 5 to 40 to 60 is crosslinked by irradiation with ionizing radiation. 2. An insulated wire, wherein a conductor is coated with the fluororesin composition according to claim 1, and the coating layer is crosslinked by irradiation with ionizing radiation. 3. The fluororesin composition according to claim 1 is formed into a tube shape, and the tube-shaped formed article is crosslinked by irradiation of ionizing radiation and then expanded and fixed in diameter. , Heat shrink tube.