JPH0322308A - Heat-resistant fluororubber coated cable - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a heat-resistant fluororubber electric wire, and more specifically,
Concerning heat-resistant fluororubber electric wires that have excellent heat resistance, flexibility, softness, chemical resistance, and aging characteristics, and are less prone to adhesion between wires and are resistant to cold flow. (Prior art) In recent years, as the required characteristics of electronic equipment and transportation equipment have become stricter, the coating materials for the electric wires incorporated in these equipment have been changed to polyvinyl chloride and polyethylene terephthalate containing various flame retardants and anti-aging agents. Heat-resistant material instead of conventionally used materials such as chemical resistance.
Fluorine-based materials, which have excellent electrical properties, are beginning to be used. Examples of such fluorine-based materials include polytetrafluoroethylene (PTFE), a copolymer of tetrafluoroethylene and 67-fluorinated propylene (FY!.P). Copolymers of tetrafluoroethylene and perfluoroethylene (PFA), fluororesins such as polyvinylidene fluoride (PVDF); vinylidene fluoride-hexafluoropropylene copolymers, 47-fluoroethylene-polypropylene copolymers ．． Fluororubbers such as tetrafluoroethylene-polypropylene copolymers are widely used.

(Problems to be Solved by the Invention) Among the above-mentioned materials, the former fluororesin is excellent in terms of extrusion formability and processability when covering conductors;
However, since the wire is hard and inflexible, the produced wire has poor flexibility and is very expensive. On the other hand, the latter material has flexibility, but has the drawbacks of poor shapeability and the need for vulcanization. In that case, 1 ton of coating obtained by coating with the above material
The wire is once wound onto a bobbin, and then the covered wire is pulled out from the bobbin and vulcanized. However, when the wire is pulled out from the bobbin, the covered wires adhere to each other, and as a result, the coated wire is removed. This results in the problem of damage to the surface of the wire. In order to solve this problem, a method has been proposed in which the conductor is coated and then the coating layer is irradiated with an electron beam to crosslink the material.

However, materials for which this electron beam crosslinking is effective include:
Currently, a copolymer of vinylidene fluoride and propylene 67 fluoride is mainly used, but this material has the problem of being extremely expensive. Tetrafluoroethylene-bolybropylene copolymer is also known as a low-cost fluororubber that can be crosslinked with electron beams. However, this material has a problem in that the wires adhere to each other due to cold flow before electron beam crosslinking.

The present invention solves the above-mentioned problems when using fluororubber as a wire coating material, and improves heat resistance. To provide a heat-resistant fluorocarbon rubber electric wire having excellent flexibility, pliability, chemical resistance, and aging characteristics, not causing adhesion between T-wires, and inexpensive from a fluorocarbon rubber material as a covering material. With the goal. (Means for Solving the Problem) In order to achieve the above-mentioned object, in the present invention, a tetrafluoroethylene-bolypropylene copolymer 50 to
An extrusion coating layer of an elastomer composition is prepared by blending 15 parts by weight of silicone rubber or/and silicone oil with 100 parts by weight of a rubber compound consisting of 95% by weight and 5 to 50% by weight of polyvinylidene fluoride. There is provided a heat-resistant fluororubber electric wire formed around a conductor, characterized in that the extruded coating layer is crosslinked with electron beams.

In rubber and some materials used as coating materials for conductors, tetrafluoroethylene-polypropylene copolymer is a copolymer that is very susceptible to cold flow. Therefore, vinylidene polyfluoride is blended for the purpose of suppressing this cold flow.

The blending amount of polyvinylidene fluoride in this rubber IJl precept is 5 to 50% by weight (therefore, the content of tetrafluoroethylene-bolypropylene copolymer is 50 to 95% by weight)
is set to If the blending amount is 5% by weight, the cold flow will become noticeable, which is disadvantageous.
This is because if it exceeds 0%, the heat aging resistance will be significantly reduced. The preferred amount of polyvinylidene fluoride in the rubber sole is 10 to 40% by weight (therefore, the preferred amount of the tetrafluoroethylene-bolybropylene copolymer is 90 to 60% by weight). This rubber composition is further blended with silicone rubber and/or silicone oil to prepare an elastomer m-sole. This silicone rubber and/or silicone oil is
It works to further effectively suppress the cold flow of the rubber composition described above and significantly reduce mutual adhesion during processing of electric wires. The silicone rubber and/or silicone oil is blended in an amount of 1 to 15 parts by weight per 100 parts by weight of the rubber composition. If the amount is less than 1 part by weight, the effect of suppressing cold flow in the obtained elastomer will be small, and if it exceeds 15 parts by weight, the aging properties will be significantly deteriorated. The preferred amount is 1 to 12 parts by weight per 100 parts by weight of the rubber composition.

In the elastomer m precept according to the present invention, a vulcanization aid may be added as necessary in addition to the above three precepts.
This is for the purpose of smoothly proceeding with the crosslinking of the rubber m precepts during the electron beam crosslinking described later. As a vulcanization aid,
For example, triallyl cyanurate. Triallyl isocyanurate Diallyl phthalate. Triacrylic formal. Triallyl trimellitate. Examples include dibrobagyl terephthalate, triallyl phosphate, and tetraallyl terephthalate, and their blending amounts are
The amount is preferably 2 to 10 parts by weight per 100 parts by weight of the material. This is because when the amount is less than 2 parts by weight, the crosslinking reaction of the rubber composition becomes extremely slow, and when it exceeds 10 parts by weight, the crosslinking reaction proceeds too quickly. In addition, zinc oxide is added to prevent deterioration of aging properties. Preferably, calcium carbonate is added. When zinc oxide and calcium carbonate are added, the amount of each added is 10 parts by weight or less per 100 parts by weight of the rubber sole.
The amount should be 65 parts by weight or less. Adding too much will cause deformity. This is because it leads to a decrease in workability. In the present invention, a uniform elastomer material is prepared by sufficiently mixing predetermined amounts of each of the above-mentioned components. The mixing at this time is preferably carried out using a Banbury mixer or a rubber kneading roll, and is preferably carried out at a temperature of 200°C for 10 minutes or more. The elastomer assembly thus prepared is extruded and coated around the conductor using an extrusion forming machine to form an extrusion coating layer. The extrusion temperature at this time rises due to the friction between the elastomer and the screw of the machine, so two of the three cylinder zones of the machine are set at about 200°C, and the head is set at about 210°C. 'C or so, and water cooling should be provided under the popper to avoid blocking in one popper. The electrical wire of the present invention is obtained by irradiating the coating layer formed on the conductor with an electron beam to crosslink it. The amount of electron beam irradiation is not particularly limited, but it may normally be about 6 to 18 Mrad. (Examples of the Invention) Examples 1 to 3, Comparative Examples 1 to 3 Each component shown in the proportions (parts by weight) shown in Table 1 was added to a Banbury mixer. An elastomer composite is prepared by sequentially mixing with a rubber kneading roll, and this composition is mixed with a wire diameter of 0. 5
A bare annealed copper wire with a thickness of 0.5 mm was coated by extrusion with a thickness of 0.5 mm. Finally, this coating layer was irradiated with an electron beam at 6 Mrad. Each wire obtained is evaluated based on the elongation rate (%) of the coating layer in a tensile test, and the presence or absence of damage to the coating layer when the coated wire before crosslinking is wound around a bobbin and pulled out. The degree of adhesion between coated wires, the breakdown voltage (KV) by a dielectric breakdown test with 1-minute steps, and the degree of adhesion between wires at 250"C and 270"C, respectively.
Elongation rate by tensile test of coating layer when left for days (
%) was measured. The above results are summarized in Table 1.
(Left below) Table I *2: Product name, polyvinylidene fluoride manufactured by Kureha Chemical *
3: Product name, silicone resin manufactured by Toshiba Silicone ■ *4
: Trade name, manufactured by Shin-Etsu Chemical *5: No damage to the coating layer was evaluated as ○, and damage was evaluated as ×.

(Effect of the invention)

Claims (1)

[Claims] Tetrafluoroethylene-polypropylene copolymer 5
0-95% by weight and polyvinylidene fluoride 5-50% by weight
An extrusion coating layer of an elastomer composition is formed around the conductor by blending 1 to 15 parts by weight of silicone rubber or/and silicone oil to 100 parts by weight of a rubber composition consisting of A heat-resistant fluororubber electric wire characterized by being cross-linked.